As others have said, you need to distinguish between a drama school (usually called a 'conservatoire') and a university Drama or Theatre Studies degree. They are very different beasts.
Unless your daughter is extraordinarily talented, she has very little chance of getting into a good conservatoire straight out of school. There are 1000s of moderately talented, pretty young women auditioning for drama school. Save your money.
If she is determined on a conservatoire training, she needs to take a few years out of education. She could work in the industry unpaid doing work on the fringe (which is quite different from amdram) or she could throw herself into a variety of experiences, including amdram. She needs more than simply an A level in Drama. She should think about auditioning for a good conservatoire in her early to mid-20s.
If she wants to go to university, it should be because she wants to be at university,not because she couldn't get into drama school, and couldn't think what else to do. I teach some Drama undergrads in combined degrees who have this attitude, and they're frankly annoying.
However, if she's prepared to really work at a university degree in drama/theatre for its own sake, one route some students take is to get a degree from a good drama department that will stretch them, at a university with a very active student drama scene, do lots of curricular and extra-curricular drama, and then audition for the various MA courses in acting etc that exist.