have you experienced a noticeable drop in the performance of the car then, i've also got a 2002 TDI 150, mines only on 95k though, and i've not really noticed any drops in performance (had her from 65K)
might be worth getting yours on a rolling road, as it could just be that you're used to the power.
in terms of a "rebuild" off the top of my head, you would be looking at a new clutch, new injectors, new cam (your cam belts will need to be done on 120k anyway), your turbo should be find but you could upgrade that to a 200 bhp + one, could be worth replacing all the pipe work on the intercooler too.
all depends on how much money you want to spend, as none of these are cheap.
i'd probably start with the pipe work, then clutch, then turbo
can't help with places in north wales.