[Solved] Initial separation question

After a long, slow decline in our marriage of nearly 11 years I've recently told my wife I wish to separate and there has been no great objection to that from her, just reasonable concern about how it will work out financially etc. We're still very much talking, and I'm living in the marital home still, just in the spare room, and our 3 children (8, 6, and 2 years) know nothing yet. Children are all ours from within the marriage, so conventional with us both having parental responsibility.

It feels very artificial though and I want to get on with moving out, along with a well-planned explanation to the children. There is general agreement between us that I will very much remain an active parent (some overnight stays with me, plus other contact, though whether truly shared care I don't know yet) and so my view is that it's a given that I will find myself a local rented place to live of similar size to the marital home (3 bedrooms). I am the wage earner with a decent job, wife is stay at home Mum, not least as eldest has additional needs.

However, wife's view is that we need to work out finances to see what 'we' can afford for me to live in first. As she would become a single non-working parent I have assumed she would seek benefits to help support her, plus child support from me in some form to be determined of course. But she is taking what I see as an extreme 'principled' view of why should she have to go on benefits. And so she is taking that view of seeing what budget pops out to then determine what accommodation I could afford to rent (i.e. my accommodation is a variable), whereas my view is that having a place suitable to also house the children is a given, with a certain (reasonable) cost, and so my accommodation is a fixed constraint on affordability of anything else.

I assume that if this went downhill to a fully court-based settlement then I would have a fairly standard child maintenance settlement to pay which would definitely leave me enough to rent what I want. But I don't want things to get acrimonious and head in that direction when they're starting out OK, and overall I think we can generally work something out.

So basically the questions are firstly just from a moral standpoint am I really being unreasonable in just wanting the 'right' to a similar house to be able to offer similar accommodation to the children? And secondly is there anything that says, even just in any guidelines, that what I'm asking for really is a 'right'? I'm sure I found something when Googling that a parent with parental responsibility does have some right to live somewhere capable of accommodating their children with them should they want to, even as the non-resident parent, but annoyingly I can't find it again. If it really does exist, I'd just like something to be able to move what I want from being just my opinion on the matter to having any kind of independent justification and support to convince my wife. Then I could just go ahead, get my new place, move out and relieve the current awkwardness even while we work out everything else (and hopefully amicably).

Thanks!