Hi IsobelRose. Congratulations on all your success
A half marathon is a great goal to have and it's one I share with you. While I haven't trained or participated in one, one of the runner Chicks on this site shared this training plan with me. It is from the Toronto Women's Marathon site.
I like that it's 24 weeks; a full 6 months rather than the standard 12-16 weeks. It certainly looks doable. While I've been running for 3 years I still consider myself a novice runner in so many ways. I think that's why this approach appeals to me so much.
Good luck and keep us posted!