SWMBOs Octy went through MOT test yesterday - clean slate

But: signs of oil leak from gearbox and I suspect the seal where left driveshaft enters gearbox. Is replacement (driveshaft removal) a very complicated operation or more straightforward? Not that I will have a go myself, I'll leave it to my garage, but I would like to know if the hole in my wallet will be gigantic or just a big one

If it's still like VWs of old, it's fairly easy. Drain gearbox oil, Undo six bolts at the gearbox end, move driveshaft out of the way, unbold drive flange, replace, refill oil.