Well, I did it. Now I've got a developed roll of Ilford HP5+. It looks as if I've got 7 or 8 decentish exposures out of the 12 - which isn't bad. Not having all twelve is due to the winder and shutter being a bit temperamental on the Kodak 66 III, and to cutting off the first one with the scissors when I was loading it on.
Wish I had a neg scanner so as I could have a better look at them and post them. I don't know whether to try to get them scanned in Tripoli tomorrow, or wait until I get a film scanner.
The main thing is, the development is actually really straight forward. I was careful with the times, but slapdash with the temperatures in the absence of a thermometer. And I cut that first exposure off, somehow. AND I was mortified thinking for a minute or two that I'd loaded the backing paper and left the film sitting out when I put the light back on. But all was well. Not bad for a first go.
Maybe I will wait until I get a film scanner, and get a Fed 2, and get into B&W film properly. Maybe I'll even think about a Hasselblad 500 C/M one day. But for now, with no functioning 35mm camera, and probably no way of getting 120 film scanned, I'm going to have to dust off the D50, and go back to digital for a few weeks. There are worse fates.