Housing costs for claimant on IS but in marital home with ex

My client separated but still lives in same jointly owned property as her estranged partner. He does not claim benefits and pays the mortgage.  My client has been awarded IS less an amount he pays towards some bills. I can’t figure out if her IS should include some housing costs after the 13 week waiiting period.

Following on from this she wants to take out a new loan to buy a property when the current one is sold.  There is quite a bit of equity. A lender has told her she would get a £20K mortgage.  Would she be entitled to help with housing costs then ?  According to CPAG she could argue she should be entitled to housing costs up to the amount ‘they’ were liable to pay when they were together.  I can’t get my head around it and it’s my last day before my hols so would like to go without this popping up in my head when I’m chillin’ on a beach !!

anyone ??