Most fan heaters come with a frost setting which was fine for me. Guess the heat in oil filled lasts longer though.
I have heaters availiable for the van, can use hot from the trailer, can fill with warm if needed and have a backup trolly and tubs system if I need to bring it inside.
I also have a little bit of ladder work each month to keep the Business acc topped up.
My winter plan is to get as much £'s in the bank as possible. I'm at the point where I have enough stashed in the business account to pay me the wage I need up to and including 5th Jan, which pleases me greatly.
It's simply a matter of being organised.
I quite like the idea of seasonal work, blasting it in summer and ease off for late autumn/winter.