IMHO forget the Garmin III Pilot!! Get yourself a pocket PC ( I use the Mio168 with built-in GPS ). You can load a digitised version of your preferred 1:500000 chart, use the moving map facility and it's just like flying with the paper chart! The PPC requires memory map navigator to run the CAA chart, and you also get the 1:250000 charts relevant to the half mil, and you also get all the airfield data charts. The PPC has a full 65536 colour display and the GPS receiver is a hundred times better than the Garmin.
Also, you can load TomTom navigator and use it as an in-car navigation system which is remarkably accurate with voice directions for your planned route.
Apart from all that it's a PDA as well and costs around £250.
Check out :
www.globalpositioningsystems.co.uk
www.memory-map.co.uk
message me if you need any more info.
Mark