Thanks (to a now very chilly) Macca!
My clocks all seem to work properly, coding out the brake sensor caused the immo lamp to illuminate, (thought the engine would start and run fine!) but recoding the keys got rid of that.
Losing the brake alert means my radio now comes up on the DIS, and my clock was never broken (i/o - idiot operator error..) so all I have left is the dimmer doesnt work, but I am convinced that is just the potentiometer on the adjuster.
Thank you thank you, you have all been really helpful, especially Simon who I cant recommend enough - he knows his onions and doesnt just leap in and try things without understanding them first - top bloke.
If anyone has blown their clocks up or has a duff spare that I could break apart, I will try and change out the dimmer pot as I cant see that has anything to do with the different clusters, ie it cannot be softcoded, surely!
Please PM me if you have a spare set of ANY A4 B5 clusters that I could test and break if needed.
Good luck Byzan with yours, if my original clocks ever turn up, you have first refusal on these ones - they have your name on them.
PS - I havent ACTUALLY driven the car yet, hope to try it all out properly tomorrow..