Made good progress today by the clever technique of inviting my brother round and letting him get on with it.
We now have the scary bits done - wiring harness in place, brake lines all routed and fuel lines where they're supposed to be. Simple matter of assembly from here on in.
I'm being really careful to make sure nothing goes back on without being inspected, cleaned, refurbished as necessary or replaced, and it's paying dividends. My clutch has been heavy for a long time - so long that I'd rather forgotten it wasn't always like that. But now I've discovered the plastic surround on the cable inner was split, and binding on the outer, and the pedal bush was seized. A new cable and refreshed bushes and it should be hugely improved. Lots of other little issues are turning up as well. The car is eight years old now, and it's probably well overdue for a complete strip and refit.
Somehow I've managed to lose half the boot floor. God knows how - it's a big chunk of wood and aluminium but I've searched the garage, the car port and the front garden, and it's nowhere to be seen. Shall have to order another one from Caterham - that's an extra £20, but not a lot in the wider scheme of things. I'm not counting, but I wouldn't be surprised if I'm the wrong side of five grand already. Never mind, it's going to be a vastly improved car when I've finished, so it feels worth the cost.