Gotcha. Presumably paid for by someone else? I'm sure those exist but I wouldn't count on it. How many hours do you have? Plan to pay your own way. The good news is there's probably never been a better time to become a pilot. You mentioned 'determined' - that's exactly what you need to be. Your life should revolve around finishing those ATPL exams and making this happen. You mentioned a mortgage - can you sell the house or remortgage it? You can save the money in a couple of years but borrowing is just more convenient as it gets you into the job quicker. It's a limited duration career, which means every year you waste you're losing out on a final years salary. Do you want to miss out on £200k for the sake of a £25k loan?
If your credit rating is any good then you'll have no problem securing funding.