Willow,
The first 2 steps are as cheap as you can get in the flying world but are vital.
Firstly, your PPL is valid for 5 years, but it is a damn sight easier to get current within that 5 years than outside of it. I would suggest you sell the dog, carpets, get a cheaper car, whatever, but keep your PPL going. Without that first step you might as well give up now. Moreover, a few hours with an instructor will rebuild your confidence, such that you may start to enjoy flying again.
Secondly, the best £400 you will ever spend is to get your class 1 medical. You cannot fly commercially without it and you need to know you can get it.
Be realistic about your route into aviation. I heard a few years ago that there were 47000 applicants for BA's cadetship with only 100 places. Now there are even fewer sponsorships, the odds are even worse. By all means, chase them (I did exectly that for 5 years until I became too old at 28, and got close, last stage for BA, 2nd to last stage for British Midland, but never quite made it).
Distance learning ATPL exems can take between 9 months and 18 months for most people and you can start them with just your PPL. That should keep you occupied for a while and you can look at means of funding your hours building in the mean time. Your funding options really fall into 3 catagories.
1. Stop wasting money renting, buy a house, let your investment grow for 1 to 2 years and then re-mortgage to free up some capital.
2. Borrow the money, only realistic in your position if you buy a house and secure any loan against it.
3. Save like a thing posessed. For Christmas and birthdays ask for money. Sell anything you don't need (amazing what you can get for stuff on Ebay!) and budget on what you do. Give up golf and windsurfing, because you can't afford to have hobbies that expensive and pursue you dream. If you can get overtime, even in a job you hate, do it and put the money aside immediately.
You then have a few options you can chase. If you can raise the cash to do hours building and potentially CPL in the US then do so. It will save a lot of money. C152's go for around £35 per hour I think. Your 100 hours PIC for the CPL would cost you £3500 plus flights and cost of living in the states or £10000 over here.
Alternatively, get down to your local flying club and have a chat to them. See if they need a hand at the weekends maybe staffing the ops desk, cleaning aircraft, whatever, but make sure you get involved and demonstrate your passion for the aircraft. Your long term reward could be anything from cheap aircraft hire to a job, part time or even full time. If you don't ask you won't get.
Regards
Obs cop