Phew!

Firstly, the extruder motor I ordered yesterday has already arrived! Wow, that was fast.
Also I have now managed to make my Makerbot order - I had tried removing all the security and privacy and pop-up blocker settings, and I'd tried Firefox instead of IE7, but in the end I did all of the above as well as turning off Norton Personal Firewall. That was really a last resort.
I had watched their stock dropping, down to only 2 motherboards left....

Anyway I have ordered:
motherboard 1.1 kit, extruder controller 2.2 kit, three motor drivers (I so want to say 3.3, but actually they're 2.3) as boards only, and a temperature sensor v2 board only.
The Makerbot charge comes to £58.11 inc postage (so far) with current exchange rate.

I have spent much of the day looking at soldering irons and solder paste. There is a lot of choice out there, only I didn't know what features were important. Thanks to some help from the forum, I now have a much better idea. I'll order it as soon as the first electronics turn up.