* [probably] MemoryMap if you only want the CAA charts / moving map
* Air Navigation Pro for something a little more sophisticated based on the CAA charts that allows for flight planning and navigation
* RunwayHD is a step up again including airspace warnings, live NOTAMs, weather etc.
* Skydemon don't use CAA charts, but it is arguably the most sophisticated GA aviation nav app in the European market right now (and will have airfield plates in a couple of weeks time)
FWIW, having got used to them I find Skydemon's charts preferable to the CAA charts (amongst other things they're vector diagrams so the words etc are always the right way up whether you want to fly north up or track up), controlled airspace is only shown in a band around the height / altitude the flight is / is likely to be conducted at, the plotting of NOTAMs and weather is incredibly useful, and the live navigation including airspace warnings makes flying with it very easy.
Andy