I just got off the phone with DEFRA. It's that those 4 are the only ones authorised for use in the UK, not that they must be administered to an animal coming from the US on the PETS scheme.
It's up to US regulations to determine what vaccine the US vet should use. The type is inconsequental to successful completion of PETS. Just that it should be inactive.]
The first person I talked to at DEFRA was totally confused by my questions (What do you mean 'inactive'?) but I got transferred to the head office and they were entirely helpful. They said I wasn't the first to be confused, and that the information could be more clear.
Thanks Reinadeluz! Things can get really confusing without background information, and it was really helpful to get some definitions from you.
Good luck with everything. I brought three cats over last year. The hardest part was the wrangling and the worry about what was going through their fuzzy brains. It all turned out fine, as I'm sure it will for you too!