I do 3.5hrs each way, once or twice a week. 2.5 hrs of that is a single train.
in the morning I do (quick), mess free makeup (mascara, brows, lipgloss), have coffee and granola, and then enjoy 2 hours of work catch up, uninterrupted by calls etc. and get ahead of the day. So- I’d say you need make up bag, phone & charger / laptop & charger, headphones, coffee and breakfast.
In the evening I tend to get a late train, so I have dinner (usually a salad or sushi), a glass of wine or gin in a tin, and deal with life admin- online grocery shopping, booking kids clubs, paying bills, holiday prep, whatsapping friends. If I’m exceptionally busy at work I’ll try and do a low-risk task that needs doing like background research or an admin task I can do mindlessly, that won’t matter if I go slowly and where I can’t make a serious error. If I’m totally wiped by the day, I’ll watch Twilight and eat a massive bar of dairy milk.
Evening essentials for me would be headphones, diary/notepad, dinner, wine, chocolate. I also take a big woolly scarf in my bag so I can get cosy as it tends to be cold on the later trains.
I prefer to squash all of my commuting into one or two longer days tbh; really enjoy the productivity in the mornings and the chance to quietly catch up with life in the evenings.