If you were that interested I would have thought you would have gone to their web site where they also publish their manifesto. I have. Aside from race, their policies have that kind of basic, obvious, utterly unthinking attitude that one would expect. So they have (had) an environmental policy that talked of ridding Britain of "all forms of pollution", I expect whoever came up with that phrase is their version of Oscar Wilde.
Aside from that, they are big on all the mundane side issues of the day - capital punishment, corporal punishment, speed cameras, Europe. The usual stuff you kind of expect from the reactionary right, allied to unclear economic policies and an array of unfunded promises to do what's right by various neglected heroes.
It's pure sugarcandy mountain stuff tbh. They do genuinely believe that with all the black faces removed, Britain will become some kind of worker's paradise, largely by racial magic, but with the help of a kind of self policing, 'common sense', fascist anarchy. I don't find it very sensible, and frankly if their opponents aren't able to make them look silly on Question Time, then they are imbeciles.
If you are hoping they have an added dimension beyond that, they are going to let you down. There are plenty of racists in the other parties, the only reason for anyone to join or support the BNP is if they are into the whole repatriation bit. Their other policies are all fairly trivial, and the BNP is in effect a single issue party.