They (the bnp) do have some policies, but I really think they'd be a disaster. Have a look at their site: www.bnp.org.uk/
I did look. Protectionism, profit sharing in economy. Increased spending on defence, increased law enforcement. Boosting public services, like health care, transport. Taking care of the old. Taking care of cultural heritage, for example, saying "no" to the monstrosities of modern architecture (I'm with Prince Charles on that, although he is a jerk in other respects). Finally, protecting environment, with the immigration question, as I see it, being basically an environmental question. Do we want some species of animals disappear? For most people, resoundly no. Then why do we want the diversity of human race disappear as it surely will if have mixed population everywhere.
Now, I am really asking. I am not challenging. I simply don't know enough, and I'm taking what they say on their website for the face value. As far as I can see, they have taken care to get rid of antisemitic rhetoric, which for me would be a decisive question in supporting any ideology. They are staunchly against islam. A big plus for that.
As far as I see, they are a party with a populist program. Their protectionist politics (not socialist) would not go down well with liberitarians, but I'm not a liberitarian. I have been looking for a party that combines the right-wing attitude regarding religion, moral values, strong defence, and free access to guns with the left-wing attitude regarding social inclusion and adherence to the values of meritocracy (equal start in life and equal educational opportunities). Therefore their program makes sense to me. So please enlighten me why they should not be taken seriously.