Thanks for the replies people.   Everything else in the house is in very good condition or will be renovated so I think I'll bite the bullet and install heating as I would really like to find some long term tenants and keep them happy.   It already has a wall air conditioner in the living area.

I've had the split cycle a/c heaters in properties I've rented and been pretty unimpressed with them – mainly because they've been fairly noisy and I'd need at least three to heat the house.   I also find them kind of ugly but thats just personal opinion.