Seat Leon Cupra R 210 surging

[mty12345]

Also would anyone recommend plug and play tuning boxes off eBay for example for a stage 1 tune to give that extra ,30-40 bhp

No definitely not mate. Go with a reputable remap like Revo or APR. Diesels you can get away with the cheap boxes, petrol is much more importamt to have a proper map.