We took a 2.2 kW gennie last year.Enough to power a full size fridge, lights, Stu's Caravan Fridge and light and half a dozen electric cool boxes. Oh, and the electric kettle.
I don't think a 720W would be enough Robbo. Fridges and Freezers run at a reasonable wattage (700-1000W) but need at least double that to get started.
The other thing to bear in mind is to think of some kind of sound insulation for it unless you want to really p*ss off your neighbours.