Yeah, there's some fairly difficult (and somewhat expensive) training and testing involved in being a HGV driver. As I understand it, one of the ways the EU helped Eastern European truckers outcompete local ones is that they could use their own countries' HGV licenses to do deliveries that were entirely within the UK and didn't have to go to the hassle and expense of getting a UK one. (Wouldn't be surprised if there was something of a race to the bottom in licensing too.)