Where can I buy with existing tenant

Property Investment

I'm in the market for another property and as I hear that more of us are selling than investing I was hoping to get somewhere with an existing tenant (just to make life easier really, and kick the problem of getting it ready for tenants down the line...)

Estate agents here in Milton Keynes don't currently have any, surprisingly. Does anybody know anywhere better than Zoopla/Rightmove to look for these - am I missing a trick? Half wondered if there'd be a load of you listing stuff on here actually, but it looks like that isn't allowed. Thoughts appreciated!