Is there any protection of your job in the UK if you are off for legitimate medical reasons?

In the US there is the family leave act. It is unpaid but protects your job. i was never smart enough to use it. I have lost three jobs due to missing to much time due to depression over the years. Two were the most recent.

How ignorant to ask how long you will be off. I often made the mistake on saying I will be in Monday under the pressure of them asking when I will be in. Then Monday came and no way I could show. I don't know what difference it would have made. I told them I was disabled, I had doctors notes. It didn't matter. I missed to much time and they let me go. I can't really blame them. They were under a tremendous amount of pressure to meet deadlines and had to replace me.