Do i need a reference from my 6th form on ucas if its been 2 years since year 13?

I finished my a levels in 2022 then went to uobirmingham that september, after 1st year I decided i didnt want to continue that course so I took a gap year

Now im reapplying for another course at uobirmingham for september 2024, my grades are above the entry grades so im not worried about that I just want to know whether I have to contact one of my old 6th form teachers for a reference or not.

You don't need for your old sixth form to act as a referee, no. But you need someone to do it. If you've spent a year at university, the normal expectation would that that you'd use someone at the uni (your personal tutor?) as your referee. Is there someone suitable?

As UCAS say, "your referee should be someone who knows you academically and can share supporting information relevant to the courses you’re applying for".

No there isnt at my uni, I didnt speak to my personal tutor once during the year. If that's the case would asking my 6th form maths teacher be better (im applying for maths). Im sure he knows me much better academically than my personal tutor does

Yup. In these circumstances, that sounds like a better plan. Given that you're re-applying to the same uni, they'll already know quite a bit about you anyway. Don't forget to include details of the year at uni in the Education section of your UCAS application.