
Unfortunately to bring a dog into UK it has to come as Cargo (though nothing to stop you being on same flight) ad you will not be able to seethe puppy until it is in quarantine kennels and passed by the Vet.
I flew to Finland in October to Helsinki as excess baggage and the Local flights too, picking the dog up in baggage along with my bags (though it didn't go on the conveyor :( ), but coming home she had to go Cargo on the approved route as we were using Pet Passport.
Without Pet Passport you can use whichever route best suits and if i is to an airport without Quarantine kennels they a Quarantine kennels carrier will have to pick the puppy up.
Your best bet i to contact the Quarantine kennels you will use and they will handle everything for you.