English and Theatre BA?

If you wish not to give it up you could do either 2 things: Just go for the straight degree and join a society that focuses on theatre, drama, acting or performance art. Or the other option is to do English and Theatre.

I don't think it would put you at a weaker position to that who had a straight English degree.

I think you should just look as whether what type of theatre the course will offer. Some it will be about the historicism and theory of theatre and drama. While some would be more about the performance and physical aspects of theatre. See which one it is, it might be both and see if it is beneficial to your life and career outside of uni.