i actually used to work for HSBC & my mother is a commercial manager there. I studied at Bucks New Uni on the modular ATPL & degree combined course and when we looked into the ability to gain a PSL for some of the guys on my course it proved difficult as HSBC only like handing out money to those with a degree!!
The information above is correct, Bournemouth, Oxford & Milton Keynes are the three main branches however any branch (business center) has the ability to help and fill in the documentation however you will need an impressive in depth business plan to succeed!!
Good Luck!!