Update

Yesterday I returned to the surgeon for the 6 week follow up after my operation. The original plan was that I would get the fibreglass/goretex cast at the two week mark, then wear that for another 4 weeks. Unfortunately, things didn't go to plan.
After a few weeks of having the fibreglass cast on, I noticed some redness around the knuckle of my index finger. Closer inspection revealed that I had a sore near the edge of the cast. It turns out that when I was typing the cast would press against my hand. Given there's very little muscle in my hand, it pushed the skin up against the bone and I ended up with a pressure sore. The OT cut the cast back to try and alleviate the problem, but this only shifted it back further up my hand.
So, the remedy was to replace the cast with a splint, a moulded plastic sheet running from halfway up my fingers most of the way down my forearm. It covers the top half of my arm, and is held on with velcro scraps. I wear a "sock" under it to protect my skin. It's not as covenient as the cast, I can't get it wet and have to change the sock.
Despite this, my surgeon was very happy with how things had healed, and gave me some exercises to do. Now I go back to to the OT to get the splint straightened to a neutral position, keep doing my exercises and go back to the surgeon in 4 weeks.
The best news though? I can drive again.