I don't know anything about floristry. However, from looking at jobs on indeed there, it would appear you are right in what you say,
Trainee florist - 1025p/h
Experienced florist - 13-14p/h
I think if it's something you have your heart set on, money shouldn't really be a MAJOR factor.
I think you have two choices: (1.) Do a course in floristry and gain experience and then employment that way. Or (2.) go in as a trainee part-time every Saturday or most Saturdays to gain experience. I assume floristry is something you could achieve promotion in pretty quickly once you get the hang of it. There is options of becoming a manager in a florist or opening your own shop and then money wouldn't be an issue then.