Avon changed the makeup of Skin So Soft, so if it does work for you, look for the original.
If Skin So Soft isn't the right stuff for you, and some places I know it isn't, then Lifesystems 50 or 25 is good, just be careful with it.
There is an alternative, Pyrethrin treated clothing. Might be worth a look, although I'm sure British MTP combats are already treated. Other clothing can be sprayed.
My choice, with the repellant is one of these:
https://ultimateangling.com/en/fishing-sleeping-bags/ultimate-night-fleece-cover