Thanks for the replies... That's kind of put a lid on it, its best I keep saving!
Sorry, I didn't expain very clearly. The extra room would ideally be used as a bedroom, but would not do this if not to regs. To regs I'd be losing a bedroom to gain access.
The first quote I was given was to regs (I think), but it involved using my small bedroom for access, which meant I was a bedroom down... so the conversation almost stopped there.
I was then offered to do this not to regs, but advised I could not use this as a bedroom, the access would be built above my stairs. This did not give the clearance (2 meters - might be wrong here) at the bottom for the entrance and a proper fire door etc needed for a bedroom.
Basically, if I was to go with the second option (ie not to regs) which I was very tempted to do, there were obviously other areas that could save money, not working to regs, bringing the price down I guess!
Thanks very much for your replies... You've just stopped me making a big mistake!
Bob