There are 4 main types of dogs that are banned in the UK: The Pit Bull Terrier, the Japanese Tosa, the Fila Braziliero and the Dogo Argentrino. If things were this simple your dog would therefore not be classed as a dangerous dog. However, the classification of Pit Bull Terrier also includes the so-called "Pit Bull Type" classification. The British government refers to this kind of dog as one which shows a substantial number of physical characteristics of a Pit Bull Terrier – and the meaning of this is vague.

It also widely accepted that any terrier crossed with a mastiff-type breed often leads to the creation of the "Pit Bull Type". However, since your dog does not fall into any of the 4 strict breeds, I believe there is room to maneuver. For example, when you register your dog you can prove that she is not dangerous in a specific testing environment.

You need to contact your local vet who can put you in touch with someone who specializes in British dog laws and who can advise you about the best course of action.