It was 18 years since I went through the recruitment process, but a colleagues son is currently on his recruits course with BTP in London. I think he is going to be working in Leeds.
As far as answering the questions on the application, use the STAR format ( situatiion, task, action, result)
Be honest, dont bull**it.
Read up on the Constabulary, if you can get hold of the Chief Constables annual report that should tell you about initiatives, policing strategy etc. Read up on this sort of thing.
Good luck.
http://www.btp.police.uk/pdf/BTP%20AnnualReport%202014-15.pdf