I presume you are going to HSBC, as they are the main lenders for Pilot training.
Based on my own experiences (I borrowed £17,000 off them) you will need some form of security for the loan, if you don't have that then they will insist you take out Life Insurance with them which acts as a security to the loan.
I didn't need a business plan, but then I'd banked with them for 6 years and had recently had business accounts with them which obviously helped.
They will want something from your intended training organisation outlining all the costs in detail and will also want to know what job prospects you may have when you finish the course (you have to blag that one a bit!!)
I dealt with HSBC in Cheltenham, the guy there was very helpful and knew about the Professional Studies Loan (some branches I hear haven't got a clue what you are talking about when you approach them!). If you want his details send me an E-Mail.
Regards,
GPS.
------------------
Aargh, that was the taxiway we landed on!