Should I leave on a high at AS or should i sacrifice my grades?

Maybe do as well as you can at AS and talk to your tutor about taking a year out if you feel you need to, spend that year working on your mental health and then come back after a year and finish the full A Level? Talk to your tutor about the options you have.

No one has ever done A level over 3 years due to mental health. People do it over 3 years if they fail one and have to drop that one for another A level so they end up doing 2 A levels and an AS in the second year and the AS is taken up to a2 in the third year. The only options are to manage the pain or if you can't manage it then drop out and do a btec.

How do you know that no one has ever done an A-level over 3 years due to mental health? Lots of people are dealing with health conditions and may take longer to complete a qualification.

In my college they havent according to my tutor and she has worked there for over 10 years.

No one has ever done A level over 3 years due to mental health. People do it over 3 years if they fail one and have to drop that one for another A level so they end up doing 2 A levels and an AS in the second year and the AS is taken up to a2 in the third year. The only options are to manage the pain or if you can't manage it then drop out and do a btec.