In my training session up to date, I have simply swum non stop. But last night was also my first experiment with taking fuel and water on board during the swim. I bought an energy sachet, and practised treading water whilst eating some of the gel, firstly after an hour of swimming, and then after another 40 minutes. I didn't notice a huge energy boost, but the idea is to sustain a suitable energy level required to keep going, as well as get used to keeping the food down. Vomiting is very, very bad, and needs to be avoided at all costs. (I know I need to train in the sea more, practising feeding, but I have to start somewhere.)
Another lesson learned from last night was that if I use the Body Glide substance AND Vaseline I don't chaff. Quite how long this mixture will last needs to be discovered, but certainly I was still coated in the mixture at the end of my session, and there had been no rubbing.
So much to learn!