OK, so fair enough, theft is theft, whether it's £50 or £5000, but there HAS to be an appeals procedure. Every company should have that. If your company won't offer one @b0rnSad I would contact a union, or the Citizens Advice Bureau.
Yes you did wrong of course, but everyone is allowed a fair hearing. I do know someone who was caught pilfering £30 from the petty cash at a restaurant some 6-7 years ago, and she was also struggling financially. Whilst what she did was very wrong, and yeah potentially a sackable offence, the manager made the decision to give her a written warning ... She is still there 7 years on, she has not put a foot wrong since, and is a valuable and hard-working member of staff.
The rules in most companies are theft = gross misconduct = the sack! But rules are meant to be broken, and some people in some companies do far bloody worse and get away with it. I used to know a manager who would go out and visit clients and customers (it would take 3 hours from 9.30am to 12.30pm,) and then he would go to the hairdressers, or his mates, or his mum's, then do some shopping, and tootle around the shops for half an hour to an hour, coming back to the office at 3.00pm.
He was permitted an hour for lunch and extended it to two and a half hours at least once a week... He was also stealing. Stealing time and hours. Pissing about like he was in his own time when he was being paid to work.
Similarly, I have known of MANY tradesmen - electricians, plumbers, carpenters etc, who do a job in 20-40 minutes and put an hour an a half on the job sheet, then sit in their van chilling, chatting to their mates, their wife, and passers-by for an hour, before going to their next job. Again, stealing time from the employer,
So there are all sorts of versions of 'stealing' and in the scheme of things, £50 is fuck-all.
@b0rnSad Do investigate how you can lodge an appeal.