I don't want to be negative but I'm not sure programming is the answer. The learning curve is extremely steep if you don't have a background in this stuff - and very tough indeed if your mind isn't inclined to enjoy thinking about database structures and logical problems and debugging code. You would have to slog away and probably pay for training.
I have a much better idea. Have you thought about training as a financial auditor? It wouldn't immediately put you at £50k but starting salaries are good. You train with a firm whilst working on the job, it is a very secure profession and once you qualify as an accountant you can easily command a salary of £50k. Working at a large audit practice the benefits are good too, and a lot of them now recruit new talent without qualifications because a lot of school leavers don't want to take on the debt that a degree involves and a degree is not needed as you are given all the training you need (i would say look at Top 10 firms but maybe not the Top 3 as probably too competitive). You would doubtless be the oldest trainee there BUT you can offer maturity, a level headedness and worldly wisdom that is VERY necessary in auditing. It is actually a fascinating job, lots of contact with clients and working in teams. Many, many audit trainees leave once qualified to go and work in another firm or to work as a financial accountant in a company (pay is often a lot better), so it doesnt really matter if you are 50 because youd likely leave and get a better job at 54.
I have known someone in their early 40s train in this way - it is very rare but it CAN be done. You might struggle to persuade them to interview you without any qualifications but it is worth making a follow up phone call to try to persuade the HR person to give you a try.
Then prepare the heck for those interviews - you would have to pass a verbal and non-verbal reasoning test, you can buy loads online to practice on. And you would also have to probably do a group interview with other candidates, so they can observe how you interact with other people, and then interviews with senior management.
Note, you have to be able to travel a bit for work, ideally have a car, and you have to be alright using computers (if you are good in Excel then that would be brilliant). Any finance experience would help - whether it is running a PTA treasury, or handling your annual tax returns, or working in a shop, or managing stock in a warehouse - something that shows you are bright and numerate.
Contrary to what you may think you do NOT need to be a whizz at maths to be an auditor. You need to be able to make good judgements about risk, capable of understanding financial processes, good at using computers, like meeting new people (working with clients is a huge part of the job) and have very high integrity.
Easy!