hey,
i would really recommend you look at all the build diary threads to have a look at how other people have gone about making their robots from feathers to heavyweights.

when i first started there was nothing harder then trying to find out what to do or what parts i needed - theres only so much that can be explained to you and looking at alot of build diaries i think would have been very helpful

i would recommend using cordless drills to start with, as they are near enough ready to attach a wheel onto once you've taken the chuck off.

i'd say get a dx5e for £70 or so, the cheaper £35 sets might say 2.4 ghz but they arnt always very reliable or of a good quality- people were talking about it on a thread a while ago somewhere on here.

if you went with 2 drill motors you would need 2 electronize speed controllers here, http://www.electronize.com/ one each of the 15 amp high power forward and reverse controllers,

then theres batteries either sealed lead acid batteries which is what i first used in my first robot, but you soon end up getting better ones and they will just get chucked on a shelf or NIMHs which are what i use from the seller vapertech on ebay.

there was a guy in a similar situation as you a few weeks/ months ago so you could mabye try finding his thread as theres aload of useful info on there.