My garage charged me 2 hrs and said it looked an awkward job but turned out to not be that bad, you could diy
The switch is on the master cylinder and is not available as a seperate item even though it is removable from the assembly.
Audi wanted £170 for cylinder, I got this one
https://www.ebay.co.uk/itm/233428279963
Just to answer myself, replaced the clutch master cylinder, car now starts ok, handbrake releases ok, gearchange recommendation has returned and strangely the radiator fan which was starting when the engine was switched off is also now normal, strange.