There are a lot of reasonably priced places on Ebay - search 3d Printing service. Other wise, just google the same, with UK at the end. Or use Shapeways, they ship UK orders from Holland, so no customs fees.
I would find a Maker space close by and buy a role of PETG to print the parts there. It is a fun build for sure. Print time is 36 -48 hours pending on print speed.
