If I were you I'd look into private tutoring at least in the short term. The best options would depend on your level and subject, and available time. If you can work Saturdays you could develop this initially without it interfering with after school times.
If primary I suspect 11+ tutoring is where it's at, unless you're interested and able to do remedial for kids with dyslexia or dyscalculia etc. For a good income you need to accept that you will be catering to families with resources; but if you can get established then you will be able to offer reduced rates to at least some (my mother did remedial teaching for years and was very aware that had she lived in a different part of the city she was in, and been willing to turn down those who couldn't afford her, she would have been able to charge more than double easily).
Other options that might get you flexible daytime work would include supporting adult education, and A level tutoring if you have suitable subject areas.
Online tutoring that might include overseas students - hence different working hours available - has been around for a while and obviously is now more an option than ever before.
At a rough calculation, if you can get £40 / hour, then you can get your £24k on 20 hours a week for 30 weeks, or 15 hours a week for 40 weeks. However, there are probably options to do more intensive work, with a higher hourly rate for small group teaching, in holiday periods, if you can make the timing work for you and your family.
If teaching itself, rather than school teaching itself, is the problem then you may need to retrain - but I would encourage you to look at tutoring options to give yourself some breathing space in which to do that retraining.
Good luck finding the right way forward for you!