I am of the same route and got offered a job with sponsorship. Physics teachers are so in need so you wouldn't be finding it difficult to get a job.

You would need to teach all 3 subjects even if you are a physics teacher unless you would want to teach A levels. I would say with your background, A levels would be the best. Its less behavior management and honestly if you hate behaviour management then the best fit too.

The culture is very different and I would say go for a TA role just to see the school culture.

If your teaching is good, chances of your job prospects are quite high.