I'm in the UK and I'm about to quit the job in which I've worked for the past 3,5 years. During that time, I got promoted to the Team Lead position.
Now, I'm about to quit, but the company heavily depends on me, and I think my manager and the founders might not accept my resignation well.
My concern is whether my current employer would refuse to give me positive references in the future. This is particularly concerning to me because when I was promoted to a Team Lead I only received internal emails announcing the change officially, but no signed documents like a contract with a new job title in it. I also have a company LinkedIn post that mentions me as a Team Lead, and I'm registered as a Team Lead in the HR system too, but I don't know if I can use any of those items as proof of having been in that role unless my employer confirms it when someone responsible for the background check reaches out to him.
What should I do in this case? Can my employer deny giving me reference checks in the future? Could I use any of the alternative proofs of being promoted to the role, as the promotion emails?