Teaching unions - which one?

[SDhopeful]

Am starting teacher training in Sept via School Direct unsalaried/PGCE
so have been advise to join a union. Any recommendations? I do not want to pay a political levy to Labour party.
TIA

none I dont belong to any
I have my own insurance

I personally believe that if you expect the union to help you when you need them then you should support the union when a strike has been called (from a ballot by members). However, I do have a dilemma about striking for pay as I think teachers are paid a fair wage. I will strike over pensions. Arranging a school trip for a strike day can be a good idea.

I want to be part of a profession where a union is a group of people who want to use their collective voice of experience to improve the quality of education, part of which is ensuring sensible working conditions for those who teach. I don't want to be a sheeple driven by an ideologue hijacking the agenda to score narrow political points...