Compression caps are available and suitable, but you do need to be fairly careful when fitting them that you tighten the joint just the right amount. You also need a reasonable amount of room to be able to turn the spanner/wrench.
Soldering will give you the most professional result and can be done in a fairly confined space - as long as you take the necessary precautions to avoid scorching/burning the surroundings.
If you really can't face the thought of soldering the joints then you can get push fit end caps that work very well. You need to make sure you've got a smooth, straight end to get a good fit, so a pipe cutter is the preferred cutting method. You can use a hacksaw, but you will need to then use emery paper on the end to remove the burr.
You branch off from the copper tubing with a 1/4" compression tee. Cut out a small section of tubing for which the tee replaces. You must use a tubing cutter to do this, any other method will cause the tube to become oval.
Install the short piece removed on the side outlet of the tee. Attach a 1/4" compression x 1/2" pipe thread adapter to the short section. If you can find a tee with a pipe thread side outlet (preferred), skip the previous step.
Connect a 1/2" pipe thread to hose adapter. When buying parts, ensure the male and female parts mate correctly. If you can't find the proper mates, get a short nipple or coupler to change gender. Use several layers of teflon tape on male pipe threads, wrapped in the direction that causes it to get more snug when the pipe is screwed in.
Attach hose and controller. After all this, there probably isn't much pressure left, meaning you could probably transition from hose to 1/4" drip fittings for the run from controller to plants, keeping the installation less obtrusive. If you use pressure adaptive drip fittings, you can better regulate the flow to each plant, otherwise the first plant will get the most water, the last hardly any.
Be careful, though unlikely in this case, as high pressure can cause drip fittings to blow apart. You also can't use most pressure reducers, as they can spill water as they function. You'll probably have to go from hose to 1/2" drip main to 1/4" drip distrubution. The 1/2 to 1/4 punched connection can leak slightly, so it should be done over the first plant.
Best Answer
Compression style stops work the same on Type M and Type L, they both have the same outside diameter (O.D., 5/8").
Type M is thinner walled and (IMO) substandard. It is cheaper for a reason, you should use Type L.
As a sidebar: it seems you are familiar with soldering since you are plumbing the bathroom yourself, so why would you use compression (or "Sharkbite") connectors? It will just set you up for difficulty when (not if) the stops start to leak-by later on and you have to replace them. Solder male adapters to your stub-outs and use thread-on stop valves.