Try The Leeds and C & G, although I think your employment/credit status may be an issue, both these are open minded with holiday lets. C & G, if they can do it, would do it at something near residential rates, The Leeds, probably 1% or so above residential.
Beyond that, there may be some 'more flexible' lenders around and you'd need to see a mortgage broker.
Good luck, I hope it works out for you.
Adrian