OK, so in your experience what would I pay for what I want, and what brand /
model would you recommend ?

Basically the pro stuff probably starts around £75-80, and as far as
I'm aware they're all pretty good. You should get a fast charger and a
couple of batteries (which means the flat one will recharge before you
exhaust the in-use one).

There's quite a few discounts about - bosch (the pro blue stuff) and
makita are the sector leaders - but don't overlook the others -
hitachi, fein(very nice), panasonic etc.

Here's the kind of thing I mean:
http://www.screwfix.com/app/sfd/cat/...43112&id=30227