Yes Sue, it will be free of lactose, so sugar free in effect.

This is my recipe

1 litre UHT milk

4 tablespoon skimmed milk powder

Natural yogurt starter

teaspoon of home made vanilla extract.

Mix all together, heat to 40 to 42 centigrade and incubate for 6 hours.

I use UHT so that I don't have to heat the milk to pastuerisation temperature and then cool back down.

Skimmed milk powder is to give extra body to the yogurt and I use 150 mls yeo valley natural yogurt, or a saved pot of the last batch I made. I doubt you can get lactose free skimmed milk powder, so you may need to omit that step

I make mine in a kiddies yogurt maker by Kidsline, it came with 4 by 150ml sized jars with screw lids, and a container that is electrically heated and keeps the mix at the required temperature- I have two of these and I plug them in to timers and leave them. They only cost me £6 each. Takes about ten minutes to prepare and then you forget it. I would think the same recipe would work in a thermos flask, possibly with a longer time for setting.

Interestingly I have looked the devices up online on Amazon, and I am shocked by the price they are now. here is a link to show you what it looks like

qid=1410360032&sr=8-227&keywords=yogurt+makers

But at £48 they are daylight robbery, I bought mine three years ago so unless they fell off the back of a lorry, someone is making a killing on them now.There are a couple of sellers on E-bay at better prices, about £12.

Hi Sue, you need to avoid the mix getting to hot and killing off the culture, so if you have a first aid kit thermometer at all, just heat to around blood temperature using that, and it will still be Ok, it is just a temperature that was stated in the literature with my kit-it is a bit like fermenting wine or beer, the organisms like a specific temperature to work at their best, but will still work if a little lower or higher than stated.

put your finger in it and test the temperature that way Sue just like when making bread about the same temperature will work. I put mine in cold at room temperature but I am using an electric machine , yours needs to be warm to do in a flask.