Gazza72:
Based on my limited knowledge of this subject I would think it would be enforceable. My understanding is that the Consumer Credit Act 1974 act was amended in 2006 to remove clauses about enforcebility of agreements. As you took out the loan in 2008 your loan is subject to the revised act.
Once you had signed up to the loan over the phone, BOS would have sent you all the information regarding the loan. Under the distance selling rules, you would only have had a limited amount of time, to cancel the loan.
If you stopped repayments, BOS would apply any default charges and these would affect your credit rating/record. After a period of you not paying, they could take you to court and obtain a CCJ.
If you are struggling to repay the loan and need advice, you should contact Citizens Advice.You should continue to make payments in the meantime.
No doubt other posters to this site will add their comments about enforcebility and the CCA as amended.
Huckster