importing can be real easy or a total PITA depending on what it is, newer than 10 years needs an SVA, cost for the test is ?200 and getting a 126 through it would be difficult,
older than 10 years all you need is an MOT, this is a piece of piss for any car, HOWEVER, post Aug 92 the car will need to be fitted with a CAT and pass the much tighter emissions test,
pre Aug 92, all you will need is RHD headlights, a rear Fog if it doesn't have one and preferably a De-registration document from country of import, but as Poland has recently become part of EU, Polish registration document in your name might suffice, best to phone DVLA and ask as rules for outwith EU and within EU vary,
getting the car over here, then finding you need a De-reg doc for it could be a nightmare.