I believe that if the entity selling the lorry is VAT-registered in the UK, it/you must charge VAT as appropriate on all supplies to an EU resident. It's then for the buyer to ascertain his/its own VAT position (maybe he can reclaim the UK VAT but then pay the Polish VAT?)
if you want to buy a car in any other country in EU check this webpage " sprowadz-auto.pl " you can use your browser`s translator to get it in english.( excluding GB - you would need to convert the rhd to lhd for the car to be recognised as registrable in POLAND and this costs depending on the car - I know that landrover freelander is convertible from £200 but all the makes and models differ - for convertion prices you can check a service just paste to google " angliki.info " but you would need someone who writes in polish )