Job nearly done. Only problem was some of the cable routing, which will be corrected tomorrow, and lack of tension on the derailleur cable caused by a slack connection at the lever end.

If anyone wants to try this, I'd heartily recommend getting a bike stand. Some of the cable replacement is fiddly, and scrabbling around on a cold concrete floor routing, adjusting and connecting cables is a pain where you can be standing with the bike at a sensible level. Shame I had no access to mine. Because of the rain, it was impossible to open the door of the shed, the wood had swollen so much.

Other than that, if you've got a full set of Allen keys plus a decent spanner kit the job is straightforward.