I could think of a few suggestions for the doctor:

Alan Davies
Peter Firth (as a sort of middle-aged Dominick Hide)
on the other hand if he could change sex when he regenerates, I could imagine either Toyah Willcocks or perhaps Caroline Quin as the doctor.

Perhaps the TARDIS could do with an external update now that police telephone boxes have all but disappeared. I often wondered why it was chosen to blend in with the landscape when so many landings were on strange planets or different time periods - what about making it look like one of those Superloos ?