Hello Amanda,
I'd suggest starting with some free study and seeing how you find it - both the content, and what level of study you'll be comfortable starting with.
You can study extracts of our creative writing courses for free on Open Learn - this course is taken from the first creative writing module on our undergraduate creative writing courses:
Writing what you know - OpenLearn - Open University - A215_1
And this course is adapted from one of the modules on our MA in creative writing:
Creative writing and critical reading - OpenLearn - Open University - A803_1
Generally speaking, the main things to consider when choosing the course would be the time commitment - a 60 credit undergraduate, module (which is what our creative writing qualifications are made up of) will require 16-20 hours of study a week for 9 months, and postgraduate modules can require a few hours more study a week.
Obviously the cost would also be a factor - how much a course costs depends on where you are resident, but in England, in the 2021/2022 academic year, a 60 credit undergraduate module costs £3168 , and 60 credits on the MA in Creative Writing costs £2210.
Naturally, this amount of time and money may be a little more than you are looking for if you want to study as a hobby: I can't speak to any courses run by other institutions, but there will be a variety of shorter creative writing courses you can study online, for example the National Extension College runs a creative writing course:
Creative Writing online course | NEC distance learning
I hope that at least helps you get started, if you have any further questions, please get in touch.
All the best
Jim