A quick list of non-paladin ways to get Lay on Hands:
- Hospitaler prestige class (Complete Divine p48) - level 1
- Champion of Corellon Larethian prestige class (Races of the Wild p113) - level 1, named "Corellon's blessing"
- Knight of the Pearl prestige class (Stormwrack p52) - level 1
Of these, only Champion is somewhat useful.
Depending on what exactly do you require of "similar" ability, you may also want to take a look at
- Touch of Vitality, class feature of Dragon Shaman (Player's Handbook 2, p14)
- ex-cleric Defiant, prestige class (Planar Handbook p44), 1 level of cleric traded
- Sentinel of Bharrai prestige class (Book of Exalted Deeds p69), 7th level
Of these, Touch of Vitality and Sentinel of Bharrai are usable - the latter being a full-caster prestige class and the former being a class feature of a half-decent class.
There may be more.
Short Version:
Maybe P is overwhelmed by bookkeeping and it's distracting him from situational awareness. Help him make a mechanically very simple character without fiddly bits or conditionals to keep track of, so he can focus on making good choices rather than having good bookkeeping. Invite the other players to support P with advice and by being good role models for the behaviour he's trying to cultivate.
Long form answer, with rambling and details.
Back in my very first RPG ever--and also my first time as a GM--I had a player whose poor choices got him repeatedly killed. Let's call him Q.
Q knew the rules and mechanics quite well, but had a very hard time applying them intelligently to whatever situation he found himself in (like forgetting to heal himself as a cleric). Even more than that, though, was his role-playing: he really really liked to role-play his characters, but that got him in trouble because when Q got deep into his character's internal motives the PC would lose common sense and perspective about the surrounding context of his actions.
It got bad. Really bad. Q's second character was killed by the party for betraying them (he had a conversation about his friends over tea with a "nice" lady). At that point I shared Making the Tough Decisions with the group. He studied it carefully, had intense discussions with me about it... and as a direct result his fourth character perished of untempered curiosity: the characterisation "very curious" overcame the common sense "half these items are cursed and my friends are begging me to stop," until the pile of treasure he was investigating yielded up a lethal curse.
After that session I took Q aside and we talked. He knew he had a problem, and he was trying to "get better," but he needed help. I'd noticed that all his PCs so far were mechanically complicated and required in-game bookkeeping: advanced casters and races with lots of conditional features and spell-like abilities to keep track of. So we hatched the simplest possible character build: nothing to keep track of. No "if you're flanking, X also happens," no spells, no per-day abilities. If his character sheet said he could do a thing, he could always do it.
We wound up with a kind of Indiana Jones flavoured skillmonkey (a rogue chassis with homebrew mods to replace things like sneak attack because tracking whether you can deal that extra damage was beyond what we wanted for the build). He wasn't optimised in the traditional sense--but since another PC in the party had straight levels in the NPC Expert class, that wasn't an issue in keeping him relevant in the group. Instead he was optimised for what Q needed: a simple no-bookkeeping character to let him focus on situational awareness and making good choices.
At the end of each session he'd hang back --along with any other players who wanted to-- and we'd reflect on the game: what worked, what didn't. We'd consult (and if necessary research) and come up with what to make sure we did again, and what we'd change next time. (I've since found that any game I run which has some form of this "reflect and plan" dynamic after every session is improved by it.)
In tandem with another player rising to the challenge and being a kind of "teach by example" role model, it worked. A year later Q was successfully running complicated wizard builds with great party dynamics and great depth of character. He was a real joy to work with, and all he needed was to wade in at the shallow end of the bookkeeping pool instead of jumping into the deepest part head-first.
nota bene: My players have tended to treat the group dynamic as one of table-level cooperation between friends. However much their characters may be rivals, at the table they collaborate to tell the best stories, and I'm also one of the collaborators. In groups where players and/or the GM act as rivals at the table level of things, I'm not sure how much my experience will be useful. It sounds like your whole group isn't really on the same page in terms of their desired gameplay experience, and communication isn't really strong. Working on improving the "friends at the table" level of things might help your game in a number of ways.
Best Answer
What you are describing is not a GM PC, it's a normal NPC villain. In the system you're using, building villains using the same character-creation rules as the PCs is also normal. Neither of them makes the villain "your PC".
It's hard to tell why you call this villain "my PC", though:
If you just wanted to be clever and make them use normal character-creation and levelling rules, then that's fine, and it's not unusual. They're not your PC though, they're just an important NPC. Treat them like a disposable pawn like every other NPC.
If you want a character to call your own and put the same care and attention into their levelling-up development, stop. Don't do that in a game you're GMing. If you want the enjoyment of being a player, be a player in someone else's game. Even GMs with years of experience mostly can't pull that off without "playing favourites" with "my PC", and a novice GM is certain to ruin the game trying to have a GM PC. The GM has a job to do, and doesn't have time for "being a player" in their own game.
As the GM, the entire world is your character. Choosing one NPC to be "your character" means they get too much of your attention and the rest of the world and game gets neglected. As a new GM, learn to walk first: learn to run a whole world, learn to build flexible plots that respond to player actions, learn to create memorable characters (even unimportant ones), learn how to pace a session.
If your game revolves entirely around your plans for this one NPC, you've created your own Achilles Heel, and one unexpected turn of the game will undo all your plans. But if you have a whole world that you've been tending to, with loose plans scattered across it, then one villain dying unexpectedly won't wreck the game at all – instead, it will be a moment of triumph your players will have earned through their own skill, and they'll remember that moment and game for years.