A rough example:

Gemm Arterton
C/o ''the little dog laughed''
Garrick theatre
1 london road
London 123 abc
Uk

Now the latter bit is made up, that is what it should look like

thank you so much for your help :)

Simply address it to the actor in question, c/o whatever play they are in, then the theatre address :)

I'm going to be writing my first VV letters very soon to Theatres and I was wondering what should I write on the envelopes to make sure that the mail is passed on to the correct person?? Thank you guys so much for your help. much appreciated :D x x