Not to worry - the 30yr experienced Audi mechanic said just to use the old fashioned method of tapping it in with an appropriately sized socket. He said he 'thinks the dealership has those tools' but he's never used them
Anyway, turns out the front crank seal wasn't the source of my leak but I took the opportunity to replace it seeing as I had the whole front end off anyway. Fortunately didn't need to disconnect the air-con as there is just enough room to move the condenser to the side out of the way.
2 tiny O-rings mating the oil cooler to the block - that's what the problem was. The old O-rings were unbelievably brittle on removal and just broke apart. So, if you've got an oil leak from the driver's side which appears to be from the sump-to-block flange then perhaps consider these seals being the actual fault. Not sure which other engines have the oil cooler in this position. Alternator removal is a bit of a pig, be warned. Wouldn't like to do that without the access available with the front end off . . . .
The front end of the engine is now nice and clean too, at least. I also took the opportunity to replace the four cylinder head plugs up top. Just rubber bungs so these were also fairly brittle after 10 years. I saw another post on here where someone had actually had theirs pop out. Two of mine were edging their way outwards so I thought replacing them would be wise. Drilled a small hole, self tapping screw and pull.
Leak free for now. Apart from what must be a fuel leak - 11mpg around town
