Hi, hope my 'story' so far will give an insight.
When I lived at home with my parents I managed to save £1000 a month for 10 months and this paid for 2 months in California to get my PPL (FAA), about 40 hrs hour building (20 in the US 20 in the UK), ATPL ground school course and all the other bits a bobs like books, whizz wheel etc. I am still doing my ATPL exams, passed 6 so far and will finish the rest this year. I then saved £500 a month for 8 months and this paid for a single engine seaplane rating in Seattle and about 10hrs hour building on a Piper Super Cub on floats (almost got an hour in a DeHavilland Beaver, but the only day the dual controlled one was free it was foggy, gutted
!)! I have now moved out as I have a job as an operations officer earning pretty good money and saving £800 a month. I plan to go to the US again for a month in October to get my tail endorsement and build a further 30hrs, this trip will set me back £4000. I am also going to build another 20hrs here in the UK in the summer at approx £3000 (includes landing fees, meals, hotels and so on). I will complete the CPL next year in June taking the time off work and hitting the course full time, I should be able to fund this with out a loan as I will have about £8000 saved. As for the IR I am not sure when I will complete this. I will judge the market (by the way my aim is not airline pilot, not that I will turn down a job if offered! I am aiming more for bush flying, perhaps Africa or the dream job would be flying seaplanes somewhere! Anyway, back to the story), maybe get an instructors rating and teach part time or something (hope tail wheel and seaplane rating will add a few strings to my bow for this). But whatever I do I think I will need to borrow a bit of money at some point and if I do I want to keep it below £15k. We will see. Just keep saving as much as I can.
Anyway mate, if you are going to do this, be under no illusion it is very hard. Get used to saying you can't go on holidays with mates as much (missed 3 years of festivals with my mates I would love to have gone to). If you enjoy a beer like me, you will find you will be cutting down due to funding issues. You can of course still do things, I have about £300 of 'spending money' a month for myself. It is also frustrating not flying for long periods but when you do fly you won't forget it!
I know I am not doing this the cheapest way (seaplanes spring to mind!), but I am really enjoying my training and my flying and thats what is important to me. Sorry for the essay but I hope it gives you an idea! Best of luck mate, we all need it!