If you are looking to get into security work the legislation that they have in place now makes it mandatory to have a security licensce.
Most employers will pay for you to get your licensce mine did, you will also need to complete your BST test.
I am not sure where you get the security licensce application though just because my work provided it. But if you are getting it on your own it is 120.00 for the one year licensce. Plus you will need to get your fingerprints done cheapest I saw it was 25.00 and you will need a passport sized photo.
Oh and whatever the BST course costs look on the Justice Institutes website at
www.jibc.com you can do it online and just go in for a test.