to be honest Louis, it all depends on how much trust you have for your garage. ask a fmaily member to recommend a garage they have used for a while.
you can demand Genuine VW parts.
if you can get over the water near Bootle, a place called TPS (trade parts specialist) are the distributer for VW Audi Skoda and Seat. Genuine parts from them, if you dont want genuine then try CES in Liverpool, actually CES in Chester maybe better for you mate, not sure.
if its just water damage id be suprised if you need a drum, you'll probably get ten years out of drums, they dont do much really. you may not even need the shoes, probably just need them all cleaning out and re-greasing, checking all the seals and joints for rust too.
find yourself a garage you think you trust first thou