Oneday78,
bit of a 'how long is a piece of string' question. But..
It's unlikely to cost you less than £30k. It shouldn't cost you more than £50k. Spend the first £25 of that on Clive Hughes' book (search on pprune for his details).
From the look of some of your other posts, you've tried cadetships but were unsuccessful. Why did you fail? Were there questions that you could have answered but didn't prepare/research thoroughly enough, or were there other reasons that might impact on your ability to actually be a pilot through the modular route? If the first, then keep trying and remember that you've still got plenty of time on your side. You're a lot younger than me for a start!
As to the rest, it's so connected with your own individual circumstances that's it's hard to give generic answers.
Good luck.