Make sure you're not on peaceful mode - this can be selected in the options. Hostile mobs will not spawn in peaceful mode.
Mobs also won't spawn on half blocks/slabs or transparent blocks, so if you're surrounded by a huge area of glass there would be no valid spawn location.
If there is a large, dark area nearby, hostile mob spawning might all be concentrated in that area - search around for caves or overhangs and light them up to force spawns to happen away from the location. (This is often stated as the cause of not being able to find hostile mobs, e.g. on this Minecraft Forum post)
Conversely, if you've lit up the whole surrounding area to above light level 7, you might be stopping spawns - hostile mobs can only spawn in areas of light level 7 or less.
You can reset the spawns in your world by switching to peaceful mode to remove all mobs, and then switching back up to normal/hard to make them spawn again.
As for attracting a creeper once you've found one:
The Minecraft Pocket Edition Wiki page on Creepers states that Creepers will follow you from a range of sixteen blocks away.
You are on Peaceful. Load your save, open the Pause menu, choose Options and from the first screen that appears (the Game options menu) slide the Difficulty slider all the way to the right.
There is no longer a "Peaceful mode" control, but there is still Peaceful mode. It is activated by setting the difficulty slider to the left. The difficulty slider now has only two settings: left and right, with no middle setting. Left is Peaceful, right is normal difficulty.
Best Answer
An iron hoe is available in the creative inventory under the weapons and tools tab. You don't need to craft anything in creative mode.