I did probate myself when my husband died. It was do-able, it was a long form and was fine, as long as I was methodical. I had to go and make an oath. You need to be very very careful to not be out of pocket, that daily interest charge is terribly high. If push comes to shove, get a clearance company in and why not sell the flat as it is, even auction, depends if the equity release co has small print. Things need to happen quickly at minimum cost to yourself. The quicker a line can be drawn across, the better for you and your own health
You need lists, banks etc, outstanding bills. I took the value of house contents at roughly the value on insurance, you could actually ask for a value from house clearance people. If you have to pay them, then there is no actual value.