Book keeping course would be a great idea. Any of the main qualifications would start off with one of those. You can even do it by distance learning if you want get started straight away, without work experience.
You were saying you weren't sure about the differences between all the qualifications.
ACA is chartered. Usually (but not always nowadays) you have to have a train in public practice, doing audits, tax, financial reporting and management reporting. You have to have a training contract with gives work experience for a minimum of 3 years and a maximum of 5. The structure of the exams has changed since I did them so you are better off looking at their website but I think there are 3 sets of exams to do before qualification. It used to be 'the' qualification and everything else was a bit second best but that isn't the case any longer. I think partly that was because you had to have gone to university before you could get on a training course so entry requirements were high.
ACCA is certified. Pretty much the same as chartered in scope but most people trained in business and commerce rather than public practice. Not thought to be so good because you could do it without a degree and you didn't have to finish within 5 years that the ACA had to. There is a bit of snobbery there though.
I know people who have been studying ACCA for literally decades (although I think they now limit you to 10 years max) but you can't do that with ACA, you get time barred which means no messing about and you have to study for 5 or 6 exams in one sitting. But, as I say, things have changed now and it is considered a good all round qualification. DH is certified and it has been good for him.
CIMA are management accountants. They do some statutory accounts and auditing whilst studying but their main focus is, as their name suggests, management accounting, more to do with the day to day running of a finance department. There exam structure was also not so strict as ACA.
Traditionally, most FDs and financial controllers are ACCAs or ACAs because their qualifications are more general and a better business qualification. However, there seems to be a levelling out of things in recent years and there isn't very much difference between them.
Finally, there is AAT (accounting technicians) which you could use as a stepping stone. It easier than the others and not such a broad training. The relationship between AAT and the other qualifications is kind of like the relationship of a legal executive to a lawyer or a nurse to a doctor. You know a huge amount but not as much as the full professional. Lots of people come straight from school and do AAT and then decide to go further and do one of the other 3 qualifications. A possible route into the profession but it would extend your training for a number of years. However, AAT does give you exemptions from some of the ACCA, ACA and CIMA exams so not as many years as you may think.
I hope that helps a bit. If I were you (I am no expert mind you), I think I would do the bookkeeping course whilst on maternity leave and then when you are ready to go back to work, sign up with as many agencies as possible looking for work. There are loads of accountancy recruitment agents so one of them ought to be able to find you something.
Good luck with whatever you decide to do and good luck with your new baby too.