I just sent my dog to UK from Florida yes paper requirements are stringent and the USDA certification alone is about $350. Then you have to have the tape worm within 120 hours of flying
all airlines are different in what they want and type of dog they will fly . Uk says they must arrive as cargo. If you fly on the same plane as him you can fly into one of the BIP airports if you are not flying with him then he has to fly into LHR .
it takes between 4-6 hours to process the animals through ARC so be prepared to wait
he is a big dog so may need a custom kennel built for the trip as they have to be able to stand turn around and lay down.
our dog was a cocker spaniel and he had to be in a large kennel to meet the needs.
there are many pet relocation services who can help if you don’t want to the tedious work there prices include the airfare but not the vet costs or kennel costs
average cost depends on size of dog
for a cocker size dog your looking at $3-4000
if you do it yourself maybe $1500 to $2000