I know this is going to sound terribly ageist.
If you were 20 years younger, I would say: Your budget isn't enough. Find another £40,000 and get on board one of the integrated school "cadet" programmes. You will be living hand to mouth for a few years, but this is your best chance of ab-inito low hour airline flying. It is most definetaly not a guarantee, but it is your best chance. These programmes have significant cost/quality benefits for the airline partners, and they are a growing part of a very stagnant industry. As the stagnation ends, they are geared up to expand rapidly.
If you were 20 years younger and couldn't raise this sort of money, then I would say find yourself the best quality modular programmes that you can afford. Prepare for the fact that on completion of your licences, airlines are not going to be in the least bit interested in you until you have a couple of thousand hours experience, with a portion of that on turbine powered equipment. Even then, the competition is so intense that jobs will be very hard to come by.
If you were 20 years younger, I would tell you that it is a brutal game that takes no prisoners. It involves an enormous degree of dedication, effort, determination, resource, money and luck, and luck, and luck! If you succeed then in twenty years time you might reasonably expect to be an airline captain with 13,000 hours or so. By then you will be around age 46.
All I can tell you in all honesty, is that people have gone into commercial flying in mid-life and have made a success of it. I would suggest that is quite a rare achievement given the realities. The founder of this website didn't start until he was 40 or so I believe, and now flies Boeing 747's for a well established operator. However I think the chances of success, as remote as they are normally for anybody starting out, are only amplified in this regard when you are 20 years behind the curve that represents "experience commensurate with age".
As to your last question, Unless you already have one, I would say PPL and see how much you like it. Then, Class 1 medical This can throw up all sorts of obstacles, even in fit people with 20/20 eyesight. Read the Colour vision thread in the medical forum, for just one of many examples.