I only know of a brand called Marigold, and it comes in little tubs. It's usually with the stock cubes in supermarkets. If there is a 'free from' section you may find one of the variations there.
I think you can have it freely- but remember it's quite salty and salt retains water. They do make a reduced salt one but I prefer the normal one. You can get it in health food shops, along with the reduced salt and organic versions.
It was a big help to me when I started a VLCD, to bridge the gaps between meals.