I never wanted to be married,never wistfully imagined dress,groom
I never wanted to have kids without being married. The rest of it, I didn't care about either. Luckily the dress etc is nothing to do with the actual legality of it.
It’s patriarchal
If this were true, more men would be keener to do it.
I don’t like the social expectations and roles bound up in marriage eg good wife, family monies etc
Ridiculous to deny yourself legal protection because of the stupidity of your friends and family. Besides, if you are the 'lady of the house', you'll find all these stupid sexist expectations are levelled at you whether you're married or not. It's a problem, but it's a separate issue relating more to how women are viewed in general than marriage as an institution.
Wouldn’t want to be a wife or change surname (i know it’s not mandatory)
No. It's not. So it shouldn't be a consideration.
I grew up in a faith were it was v much expected to get married and marriage was the manifestation of serious relationship.
Again, this is about personal associations. It doesn't mean a thing legally.
All this aside, you of course do not have to get married. Nobody does. It's just that IF you did want the legal protections (and you may not, I don't know), none of these are good reasons to refuse them.