It's actually pretty easy. You're not going to L3.
You can get an fATPL for £40k if you go modular.
Get a day job, then get a weekend job or deliver pizza in the evenings. Give up smoking and drinking. Move in with your parents. Don't have kids or expensive hobbies. Get a few credit cards but clear them every month. In 24 months you'll have half the money. Borrow the rest. You'll be an interesting candidate at interview.
If you're really smart, use those 24 months to pick up your PPL and ATPLs via distance learning.