This happened some months ago.
I work in IT, and I gave notice at a well-paid job (50k) to move to a role with a higher salary (58k). As with most senior / technical roles these days, it was a 3-month notice period.
In the two days between my old role finishing – and me training my replacement – and the new role starting, the new company made the role disappear. I couldn’t go back to my old job, but the new one didn’t exist anymore.
Fortunately, I had a signed contract. The subreddits on UK law didn’t have much advice (most similar posts from the past lacked replied, and I received no reply), so I spoke to ACAS and Citizens Advice.
Short story: The company offered me a month’s notice pay. I threatened to sue the company for breach of contract. They offered me two months pay. I told them to give me three. I got three.
Don’t let these bastards ruin your career, as they (sort of) did mine.
Silver lining: I leaned into my side business, which is going well, and I’m not sure I’ll ever have the appetite to work for a corporation again.