Your options are basically to save up/work for the money and postpone training until you have it, find an extremely generous friend/relative, convince someone that it is a sensible idea to use their property to secure a loan for you or to reduce the size of the loan required to be able to get it unsecured.
By suggesting you look at other schools people are trying to help and essentially suggesting the last option, I personally - from starting with a PPL and ATPL exams done was able to complete the rest of my training for almost exactly the £25,000 figure mentioned with regards to unsecured loans.