Two of the most tightly timed requirements in this whole process land in this final week. The Animal Health Certificate has to be issued no more than 10 days before travel, so book that vet visit for a date inside that window, counting backward from your actual departure day. If you have a dog, the tapeworm treatment needs its own separate appointment — 24 to 120 hours before you actually enter Great Britain, which for most routes means it's booked for a day or two before travel, not the same week loosely.