Soarfeet,
The Ordnance Survey provide much of the data depicted on the CAA charts & the OS are zealous guardians of their copyright.
Memory Map have been the only digital providers of CAA charts, first on Windows and now iPhone/Pad; the Android version is expected in "the summer". High quality, zoomable raster charts at £20 a chart, also comes with desktop software.
(If you can find someone who can give you pre-2010 versions of MM CAA charts, you can use them with
MM Tracker.)
There are any number of free mapping software available for Android, but you would have to scan & calibrate a paper chart to use them. You could always buy a MM chart for your desktop & screen capture & then calibrate the jpeg. If you're interested, I'll provide some links. These software can also use Mobile Atlas Creator (non-aviation) maps.
Airspace Avoid is an interesting, if pricier, alternative. Unfortunately, they don't offer the UK charts as a background, probably because they have been unable to get OS permission.
There is a freeware, crowd sourced vector mapping aviation nav. software available for Android. I find I need to RTFM a lot to use it, & I prefer to check the airspace file along my route carefully before I rely on it.
XCSoar is designed to be used for gliding but you can get rid of the gliding stuff & use it as a simple moving map with a plotted route & airspace warnings.