I'm afraid I'm with bookworm and think your response to them was quite rude!
I managed after splitting from ex and had no money, no property and no real support network.
I put in a claim for benefits (which is still a possibility for single mums with children under a certain age) and set about finding a job which luckily I did fairly quickly - but it was a better economy then and not the employers market it is now, although as you've not been out of the market long you might be ok.
You say childcare costs would wipe out a potential wage, have you taken all factors into consideration? Have you checked what benefits you would still get if working and using childcare on the online calculators that are available?
You also need to remember that childcare costs especially at the highest cost point, are temporary and getting back into work sooner rather than later not only means it will likely be easier but also means you'll be back building your cv/career, acquiring the benefits of longer service.
What exactly makes the flat so unsuitable for you and DC? Is it REALLY unsuitable even as a temporary measure? My dd has almost always lived in flats as do many children. Doesn't do them any harm.
All that said I wonder if all your excuses "explaining" why you can't leave are really due to you not at heart wanting to leave? Are you hoping for a reconciliation?
If so then you need to be proactive in achieving that, no you can't do it alone but you can instigate change.
Resentment, hormonal fluctuations, low mood, sleep deprivation/tiredness can all damage libido.
Is it possible you have low level pnd that isn't being addressed? Is your husband open to counselling, parenting classes and making the necessary changes?
Nobody has to stay in an unhappy marriage, but equally relationships go through ebbs and flows especially after major life changing events like becoming parents and when there are "external" stressors like refurbishing a house and it may not be the case the relationship is definitely over.
Lots to think about