If it's just acting, that makes your life a lot easier, OP, because unlike dancing or even singing, it doesn't require high quality early training in the same way and maturity counts for a lot more.
Dd is currently at drama school and knows a lot of older students/ex-students from drama schools all over the country. As far as she can tell, there doesn't appear to be any correlation between having worked as a child performer and getting work as an adult, or even really between having trained somewhere like Sylvia Conti as a child and getting work as an adult.
So for a career in acting, there is no reason the local am-dram or youth theatre, followed by drama school as a young adult, shouldn't meet your dd's needs perfectly well.
What she needs to do now is get as much and as varied an experience as possible, be part of as much as she can, and read as many plays as she can. Find out where her interests lie but be prepared to try a bit of everything.
Taking a few dance classes is almost certainly going to be good for her in any case (she won't be able to learn acting without working on movement), but if she hasn't shown a passion for it yet, then I agree with pp that it's almost certainly not what she will be doing.
When she is older, the big drama schools run very good weekend or summer courses that can help with individual aspects, such as audition technique.
Or she might decide that actually, this is just something she wants to do for fun- and that is also a valid choice. Am-dram will still be there.