For the many Mumsnetters looking for work-life-balance I just wanted to put in a plug for the Higher Education sector.
I struggled on for several years working part-time in my pre-parenting job in a big IT consultancy, but never felt as appreciated, and my performance ratings gradually dived. I was almost ready to re-train from scratch in something more part-time-friendly when I stumbled across the HE Sector as a rich source of IT jobs (and they need plenty of other generic skills too).
HE may not pay as well as some other sectors, but if you're qualified/experienced in something they want then don't be put of enquiring about part-time hours, even if the job is advertised full time. Most universities have Athena Swan targets for recruiting more women and so many recruiting managers will be receptive to those sorts of queries.
I've been in HE for about 2 years now and have seen many jobs going to very under-qualified applicants, for want of anyone with the right skills applying. They don't seem to spend very much on advertising the jobs, so they get a lot of "insider" applicants from other institutions, but often what they really need is people from other sectors to breath new life into projects.
Try jobs.ac.uk for starters or just keep an eye on the jobs pages of your preferred institution. If you can commute to central London, then there's loads of choice. The big universities sometimes use agencies to recruit, but for part-time queries it's best to go direct to the recruiting manager if you can get a contact name.