Definitely don’t have your breakfast before riding, afterwards is best. Otherwise you will end up being “starving” a couple of hours later. I try and leave it as late as I can, then I end up eating less throughout the day. I just have black coffee before riding and when I get to work.
I also would advise changing to water in the porridge- I make it with boiling water and cinammon. Leave for 15min and then microwave – the liquid turns more milk like.
Myfitnesspal is good, but if you can’t be bothered then start to weigh your portions of your porridge. It is quite suprising how many calories are in a small handful. I use 280ml water with 50g oats. I also put some chia seeds in from Aldi and brown linseeds from Tesco (Aldi linseeds are ground but mixed with sugary things)