It’s getting very nippy at night now. If you still have tomatoes outside, I would cut off the trusses and bring inside to ripen. If the frost gets to them it will be too late. I lay mine on an old tea towel in a shallow box and cover with a couple of layers of fleece. Try adding a ripe apple or banana with them. The ripe fruit give off ethylene gas which helps to ripen the toms.
If you have a slightly heated greenhouse for your tomatoes you can still wait a bit with cutting off the trusses and if you grow your tomatoes in a large container try to bring that indoors. It really is worth it. A sheltered lean to greenhouse or a conservatory is the best bet to grow late tomatoes in. I wonder what is the latest time to sow tomato seeds, late May – early June? I always sow mine late March – early April.