Facing separation - where to live?

[SatNightIn]

My partner and I have been unhappy together for a long time and a few weeks ago decided to separate. Have been together 5yrs and have a 3yr old son we both adore and we live in partner's rented apartment which he's been in for 25 years (has a protected tenancy agreement so won't move). He doesn't want to try counselling as he thinks there's nothing to salvage but wants me to either stay as flatmates till ds starts school (not till sept next year) or to live nearby and has offered to help with the rent, or a mortgage if I could buy a place (and he would co own). He also wants 50/50 custody which I have explained will be unrealistic to begin with but he is happy to work towards it.
I have no idea what to do next. I have part time work till november but rents and houses around here are very expensive and though it may work in the short term, can't see how the finances will work down the track. Also he's bad with money and I just found out today that he spent 5k of joint savings that were in an ISA in his name and am not feeling comfortable about relying on him for rent/payments.
He's also taken a back seat with parenting, often working long hours and not taking or planning many holidays. I've felt pretty much like a single parent up till now, with very little support when ds was a baby (my family live 300 miles away, his are near but there are problems and he keeps a distance). He blames me for our relationship breaking down and can be difficult to deal with (posted previouslyon relationships), good side /bad side, quick temper often criticizing, sometimes infront of ds so things very strained and feeling stressed and overwhelmed by prospect of single parenting. Have been to counselling alone and counsellor thinks he's depressed but he dismisses it - and counselling.
Where do I go from here? Should I stay local, knowing I may have to move again in a few months due to finances or find a cheaper part of London to live in where I can manage alone and get to work. Hours are long so need help with pickups and drop offs. Also have to apply for school place for ds by next Jan so want to keep things as stable as possible. Anywhere I can go for advice?

[somanymiles]

TBH would get legal advice asap. Best not to move out of the family home if there is a chance you can get him to leave. Not sure what that would look like with a protected tenancy but frankly you need the security of that flat more than he does.

[SatNightIn]

That would be a solution and have suggested it but he has such inertia when it comes to doing /organising anything not work or hobby related. Full of promises and suggestions but doesn't follow through in my experience so would take months for that to happen and in the meantime am going nuts. Will ring CAB tomorrow though.

Getting very mixed messages and feeling so confused. He sees no hope in relationship yet wants me to be around all the time to do family outings, food shopping, cut his hair, let his mum see ds, organise holidays etc etc. Latest is to buy a place using my savings as a deposit that he can invest in - is that a mad suggestion? I dn't even know if we can co parent yet...