Thanks for all your replies, which I have only just seen.
We got a really good deal on the Dakota 20, so went for it...we are just waiting for it to arrive now. (I hope it's ok - especially as so many replies were in favour of the eTrex )
I've asked elsewhere in the Forums if there's someone who lives near us (Peterborough, Cambridgeshire) who would be prepared to give us a bit of guidance.
Looking forward to doing some paperless caching!
Smartrascal