Having a pet passport won't automatically allow you in the UK. We were refused to board the ferry as we needed to get an additional deworming. But the animal control helped a lot, found us a vet at 8pm, a taxi, booked us in a hotel and told us to come back 24 hours later. Vet 95 euro, taxi 73 euro, hotel almost 100 euro. I told the guy at the hotel that I felt stupid for not checking. He laughed and just Said that it happens 4 times a week and keeps him in business.