You can have an offline map layer by just downloading and saving one of the free maps from the link in my last post to your phone. They're not great for rural caching, but they are better than no map, and no data charge because they are off line obviously.

You don't need memory map. Though if we can make it work with c:geo and you don't mind spending some money, I think the maps would be a lot better.

See attached screen shot of the free england map working with c:geo.


Edited to add, I could create a few users guides for here on this subject, but if wanted it wouldn't be for a week or so. If you get to the event at the water park I can show you how I have set my phone up with these maps.