If you put the boat on the market in England, or anywhere in Europe, you will definitely need to pay the VAT. But you can pay it anywhere in the EU, and the rate varies. The thing to do may be to stop in the Azores and pay it there. Last I was there (quite some time ago) the rate (13 percent) was lowest in the EU. Midatlantic Yacht Services in Horta on Faial can help with this. I'd get in touch with them and query them on the topic.