can only speak from experience but I have treated -£200 as £0 for the last 5 or so years in both my account and our joint account. And I have had way way way worse overdrafts than that in the past and quite a shady credit card 3 year abscondment. Mortgage advisor didn’t think any of this would be an issue, and still worth having me on the mortgage even though I earnt next to nothing compared to my wife at the time.
I’ve never failed one for renting (aside from one when I was contracting rather than full-time) so hopefully that is a good sign. Never missed a rent payment, never missed a phone bill (or at least not for a decade) it’s the overdraft that worries me.
Your overdraft limit is effectively treated as credit (you might not realise it, but when you agreed to have an overdraft, you will almost certainly have technically signed a credit agreement), and so going into that limit, but not exceeding it, is totally fine.
Check out these guys: http://www.firstmortgage.co.uk/ We just bought a house and would recommend their service a hundred times over. They sorted us out with a good mortgage (despite my girlfriend only working a 3-day-per-week contract and having overdraft/credit card debt) and helped us get some good insurance policies in place. Their service costs the magnificent sum of sweet f.a. to the buyer as well (they take their cut from the banks/lenders). Honestly - best recommendation you will get if buying a house.