We are in a very similar position and look to have just secured something, although it was outside of OpenRent.
My experience with OpenRent was pretty poor, we had one guy all but offer us a place then take it away 3 days later stating we needed to convince him we deserved it and he didn’t believe my earnings as self employed… you can get some real characters on here.
Since we can’t be in UK just yet and needed a place ready for return, that caused problems since we couldn’t be there in person and despite half of the adverts saying remote viewing possible, the contention meant it ended up going to someone else who viewed in person before I even got a reply.
My experience has been that self employed or unemployed you’ll probably need to pay 6 months + deposit on a 6 month contract - even if you can prove income/previous earnings. You will likely need a guarantor as you have no way to pay rent right now (or maybe a big bunch of savings might help with that?). Credit rating probably isn’t going to be the ultimate factor on this one since you’ll probably have to have a guarantor anyway.
If you can pay up 6 months ahead + deposit you could look at some of the places like fizzy living, tipi and the forge Newcastle - they have some bills inclusive and seem to be a bit more accommodating to those returning to UK. That was our next avenue.
I hope you have better luck than we did on here!