When the low warning came on it took no more than 0.5 litre to top it up to the maximum.
The headlight washers are now working perfectly, after the re-pipe.
The pump was cracked while trying to get it out, so that is being replaced FOC anyway under parts warranty along with a new seal. Garage told me the level sensor was integral to the pump, at least on my '02 S8
Car should be going back in on Tuesday - the pump is the last thing to come into stock! They have the seal and the pair of washer jets which I'm having done as well as they're a bit lacking in spray pattern.
On the wheel front, I'll see how many of the wheels need attention - he forgot to check them all before getting it off the hoist, so he said he'd let me have a look as well when I take it in again and he'll point out any problem areas on the wheels as we go round.
Given how bad the wheels are round here I'll just wait till I find another mega pothole and will file it with the council to try and get some money back. Luckily the tyres seem fine.