There is a book I found massively helpful to get us started into co-parenting while apart. It honk you can still find it in Amazon, is called “putting children first, a manual for separated parents”.
I have found that while the two of you protect your communication by being civil, diplomatic, understanding of the other’s issues and choose your battles, the children will be fine. It is when you stop talking that every little problem is amplified and resented that life becomes hell but I understand this is not on our hands some times.
It is easier to survive as a single parent than to survive as a single parent carrying another adult who is constantly tripping you down or giving you a lot of extra work. I found it much easier to cope with house chores, child’s care and behaviour on my own than when dad was around, I was definitively better organised and much more relaxed raising DS single handedly.
There is no way to avoid the money worries but in balance if you think you can afford to pay rent in another place you are already in a much better starting position than many people at the time of split.
To find how much help you can be entitled to visit entitledto.co.uk
With regards to the mortgage, don’t automatically assume you wouldn’t be allowed to take it over from him: there may be the possibility that if he is the main earner and you become the resident parent, you may get a higher percentage of the equity of the house (bigger deposit for the next mortgage). Find an independent mortgage advisor who can search for the best mortgage for your circumstances as there are some providers who will consider child/spousal maintenance as income as well as universal credit, they are difficult to find hence the need of using an advisor but for most mortgage products these advisors work on commission so this doesn’t represent an additional cost to you.
I think most divorced people will tell you the same, that it was more difficult to take the decision to leave than deal with the changes that came out of it. The most common regret is not leaving but not living sooner. One good reason to leave sooner is because your chances of co parenting efficient as separated parents are higher if you leave while you can still be rational and considerate to each other (before you are so angry you don’t care at all about the other)