It's always a risk buying a car at auction.
Definitely worth getting the parts on eBay either new or used and getting a garage to fit them.
Cheers
Steve
See if these are any good:
https://www.google.co.uk/amp/s/carmanualshub.com/audi-a6-pdf-workshop-and-repair-manuals/amp/
https://www.downloadworkshopmanuals.com/index.php/8-workshop-manuals/69-audi-a6-workshop-manual-download
This last link ive used before:
https://workshop-manuals.com/audi/
Exhaust wise, I'd look at Powerflow for the exhaust. My brother and mate both have had them and they're great 👍
I'd look at your nearest remap specialists. But for best results you want one with a dyno.
Cheers
Steve
I believe the reverse lights issue is down to the reverse light switch located on the gearbox. When it fails it can cause the lights to come on.
Wipers could be a stalk issue.
Petrol definitely makes sense living in London abd the 1.8 is a good engine. If the model year you've given me I'm guessing your after a b8 model. Here's a YouTube video buyers guide which should help:
Service history is very important with these cars and you'll need to see when the cambelt and water pump was last changed. Also see how the clutch feels. As both of these are expensive jobs. Also make sure the air con works as it too can be expensive to fix.
Cheers
Steve
Welcome to the forum, you'll find the members on here are a friendly and helpful bunch 🙂
What year roughly are you looking for band are you looking for petrol or diesel? Manual or automatic?
Cheers
Steve