So interesting to hear different experiences.
I'm a DC in a SE force, have nearly 19 years in and am a transferee so have worked across other forces.
In my experience having part/time or flexible childcare arrangements massively depends on your role, first, and then line manager.
After I had my first DC I went back to work PT on response only 2 days a week, that was great for me but probably not good for the job. But they accepted it as I could still be late off on those two days, and I was experienced (and a hard worker).
I then moved to safeguarding and continued my 2 shifts a week. It wasn't popular by the rotas I worked with, but it suited me and it was accepted. I was still useful to the teams so it worked.
I've only once in 10 years known a Flexi response officer. (She used to work permanent nights and had to finish at 6am to get home to sort the kids out 🫣)
I then worked in DA for a few years, increased my hours to 3 days a week (to answer previous question @Solace123 it's not a popular role because it's fucking intense - you have prisoners every day, can't progress your investigations, and the poor ppl we deal with often have cyclical, toxic lives and we see them time and time again so it's really dispiriting to spend 23 hours on a remand, and next week she's withdrawn, you're still progressing it without her but then after a month they're back together and she's getting beaten up again; the risk level is high; little support from other agencies, and there's seemingly no recognition from SMT how hard you work for generally poor results. The people who do work there are either 1) super passionate and want to be there 2) there against their will because there's a short fall and they're back filling from response or 3) want to be detectives and this is an excellent starting point for the role.)
So, in DA we got off late more than on time, multiple weekly late/overnight/remand cases.
I think you'd be much more likely to have a pattern accepted where you say I would like to work normal shifts (including being late off if necessary) Weds-Fri or Tues-Sat (whatever suits you) than 'every day but only 9.30-17.00' as you just can't stick to those hours. It really leaves ppl in the lurch when you say 'I have to go now I can't so that remand/court/sudden death/case file'.
That said I don't think you'd be able to start out on a Flexi or PT pattern? Something to ask.
Have you got a HR email or recruitment dept you can ask?
Both my current CID line managers are mums, one a single mum, and our DI is a father of two and everyone just 'gets it'. Family is seen as sacrosanct and so if you NEED a day off they'll move heaven and earth to get you off, we often get shift swaps and even OT authorised to cover AL requests.
There are operational exigencies and if you have cancelled RDs and can't get cover, or court days (I don't work Mondays and they ALWAYS seem to be on Mondays, and seemingly just pick my fucking rest days...) then you do just have to rearrange things.
I am Part Time but when I'm in, I'm in and I don't mind if I'm late (started at 7 this am and finished after 7 this eve, finished late yesterday too, and twice last set!)
I work one every three weekends and a mix or E and L. I only have to do 6 Nights a year (did 10 years in uniform so this is a dream!!).
I can only do this because I have a really supportive DH, and nearby/helpful parents, I don't know how it'd work if I was single.
Having said all that, I really love my job, every post I have seems better than the last (I am naturally optimistic!) and having spent so long in uniform just makes this side of Policing a doddle!!
We are helping a very vulnerable portion of society (victims and suspects).
I never leave work and wish I didn't do my job. I have a sense of pride, or contentment about knowing I'm doing my best for some very horrible and/or poorly people.