I started on a grad-entry programme in the UK at 26.
About 60% of my cohort had just come out of life science degrees or had taken 1-2 years out after. So the majority people were 22-25. But the remaining 40% were older, the oldest being 32 (who had a physics PhD)
I think it's ok to start at 32/33. Any older, I'd say probably not. Being older does give you a big, big advantage over the younger people throughout the degree. I had done a Chemistry degree, and tbh at least the first 3 years of medicine are much easier than my chem degree was. You'll probably find the same regarding physics. I'm in 4th year now though and it is stepping up pretty fast though. It's not difficult, but the quantity of knowledge required is immense.
I will hopefully graduate next year (2022) at 30. I find it ok at my age, but it is a bit frustrating after a few years of studying, knowing that I have had a job before and regularly being treated like I'm much younger than I am (as I'm now being taught with the non-grad-entry students). The idea of being an F1 and F2 at age 31/32... it's not too bad but it's not ideal. I'm not looking forward to the night shifts and intensity. I think if you're a relaxed person, though it's not as bad as people say. Keep in mind that the majority of F1s are 23-25 year olds, more than 50% women, they tend to be anxious people and while they are damn smart, they don't *tend* to be naturally gifted intelligence-wise. So when people say F1 and F2 are super stressful and you don't have time to eat or pee, you have to keep that in mind. A wise junior doctor once told me the greatest skill he picked up was to walk slowly. If you rush about everywhere you give yourself more to do and you wont have as much of a plan when you get there.
And once foundation training is over I can become a GP within a few years and the money, the status, hours and commitments become much better.
I certainly wouldn't want to be doing foundation training or core training past 40.
Sorry, bit of a ramble... any specific questions just ask.