Pot them up and keep in your greenhouse over winter. If you have no heating and need some I have seen the following suggestion but not tried it out:If there are any really tender ones make a little mini greenhouse inside the big one. If that still isn't adequate you could try adding a long lasting candle under a inverted terracotta pot making sure enough air can reach it to keep it burning.

That’s interesting .. many thanks Sue. More or less what my practical OH suggests 🙂.

Good luck then!

Stera, I'm going to try your tip of a greenhouse within. It could help with the slug problem too.

Tell us next year how it went please. There was quite a long discussion about it n Goy a few years ago.