My name is Nora Manca, I am Artistic Director of the theater company Storefront Shakespeare in the United States.
If your daughter is determined to be an actress and there is nothing else she would like to do, it is possible for her to earn a living at it, especially in England where theater companies can get money from the government (sigh).
As for headshots, just have your friend with the nicest camera take some head and shoulders shots of her in different poses with nice-but-natural hair and makeup. Then print them to 8x10 or piece of paper size.
Attach (usually stapled to the back) a resume with her name, contact info, height, hair and eye color, as well as any special talents or skills (like being able to jump rope, snap or play the recorder) along with any experience she might have. You can always cut out things later, for now any school play, poetry recital, public speaking experience should go on her resume.
School and community theaters and drama clubs are a good way to get her feet wet and make sure she does actually want to pursue acting professionally.
Even if you can't afford acting classes, perhaps her school would offer some? She can also prepare her mind by reading books by and for actors. I recommend that she starts with An Actor Prepares by Stanislavski, simply because it is a good book and he completely changed the way actors approach acting. I also recommend to her that she read and try as many different "schools" or methods of acting as possible since they all have interesting insights to offer and no one is perfect.
She should start memorizing and developing monologues (especially contrasting styles: comedic, dramatic, modern, Shakespeare, ect) and try to stay away from the popular ones that everyone knows. Actors memorize monologues for fun, it is good practice.
I highly recommend that she get at least a little dancing and singing training, even if it is just from YouTube videos (there are a lot of great one out there, I like the "Expert Village" series). So much of theater demands the ability to sing or dance or both... it with open up a lot of possibilities for her, there is often singing and dancing even in productions of Shakespeare.
Doing yoga is also incredibly helpful for actors. Not only does it tone and make the body more flexible but it focuses the mind. For actors it is really important for them to be "in the moment" and not stuck in their head thinking. You can also find free yoga classes on YouTube.
Being a professional actor is really all about being tenacious. You have to be persistent, keep going and keep trying no matter how many times you hear the word "No."
She should try to be memorable in a good way at auditions, let her fun personality show through, even if she's nervous. Also, at auditions, always, always, always be super prepared. Know as much as possible about who and what you are auditioning for and know your monologue backwards, forwards, inside-out and up-side-down. Have a character and movements (please don't just stand still) prepared and be prepared to change both at a moment's notice if the director asks you to. Tell her to practice doing her monologues for friends and family and each time have them ask her to change how she does it in some way (happy, sad, angry, fast, slow, silly, playful, ect).
Tell her to break a leg and never say the name of the Scottish Play in a theater (unless her character has to while she is acting in said play ;-)