Choices are in your hands.

I think that Willy Russell chose to end the play with Rita cutting Frank's hair for different reasons: first, as a way of showing that she wanted to acknowledge somehow all he has done for her; secondly, because she wants to help Frank to built his new self Haven't you ever change your hair style in order to change your mood? It is one of the most common ways of starting a change in our lives finally, because this is a very good way of showing us that the new educated Rita still keeps her essence and doesn't forget about her past: she has changed immensely but, at the same time, her cutting Frank's hair shows that she is still the hairdresser who was eager to learn and who is still eager to learn. Both Rita and Frank are still ready and waiting for learning.

What I want to add is in this scene we can perceived the word CHOICE . I think she had different choices since the moment she decided to start studying and as she said, she chose "her".But what Trish'attempted suicide taught is that she can chose how to live and thanks Frank because thanks to his help she had a choice.

To say goodbye, somebody who is "better educated" would be somebody who has accquired tools or strategies to make their own choices more autonomously, or has widened their range of choices, or can see themselves as better able to take wiser choices