As Rob mentioned, I bought my last boat in France, and before that I have bought another in Spain.
My thoughts would be:
Buying in Europe is very straightforward and the paperwork is simple - generally there is less expectation of a paperwork trail tracking all the way back to the original owner. Brokers rely more on a legal statement of ownership as a binding contract base, which should be ok with an established broker - BUT be careful if you then bring the boat back to the UK as when you sell it you may be expected to have more comprehensive paperwork.
You will have to pay VAT on the value of the boat when you import it into the UK (a Brexit bonus!) which will also include transport costs. This needs to be accounted for in your budget.
Road transport costs are almost certainly going to be higher than you think. You could be lucky and find a boat transport company looking for a return load, but it would still be in the thousands of pounds. Driving the boat back is viable, but the fuel cost and wear and tear needs to be budgeted.
On a boat of the size you are looking at, I think the deal would have to be exceptional to justify the extra cost and inconvenience, especially when you add on flights, hotels and car hire to check the boat and then collect it if you decided to go ahead.
Sorry if this is talking you out of it - but better to know what you are taking on beforehand.
I drove my Rodman from Bordeaux to Chichester, then to Holland and shipped it New Zealand, where it now sits waiting for Covid rules to lift. That was a much bigger project, but I knew the full costs before I started and it was worth it.
I hope that helps, but PM me if you want more detailed advice.
Ian