Aware works great on the ipad, and gives you a great representation of the CAA chart and airspace warnings before you enter them. It is also great value for money at only 25 quid for a single Chart. You can use it on the iPhone as well for the same outlay.
If you want a bit more functionality Runway HD gives you the southern chart and full Pooleys iPlates for 75 quid at the moment.
I'd certainly recommend it.
