In reply to all:
Thanks very much to everyone on the thread for their thoughts, commiserations and exceedingly kind offers of help. Two people emailed me after seeing the thread and offered to help, and Gribble/Graham not only offered me jacks and tyre levels but to actually come out to the car and lend me hand. This we did on Monday night in the pouring rain and darkness, although thanks to Ford's bizarre idea of having some sort of thin metal caps over the wheel nuts we were thwarted - three of the nuts would undo but on two, the caps spun on the underlying nut and broke. It is a nut underneath but it appears to be an 18mm size!? And neither of us had an 18mm socket to do those nuts. Cue, two slightly soggy and frustrated men standing a dark, wet countryside lay-by doing nothing more dubious than cursing a major automotive manufacturer.
Anyway, I figured that even if I got the spare wheel on, I was still going to need to take the flat tyre and wheel to Kwikfit or similar, so looked up mobile tyre fitters as an alternative. I found someone and called. He agreed to meet me at the car today after I finished work, but at lunch time he WhatsApped me some photos saying he had been, put the new tyre on and the car was good to go, and to pay him when I got a chance! Pretty good service eh? So anyone in and around Sheffield needing new tyres should look up "Mobile Malc" - heartily recommended!
Thanks again everyone, and particularly to Graham: enjoy the wine and lets have a go at Tower Crack some time soon eh?
UKC really is a nice community - cheers all.