If you possibly can restrain yourself and not go for a longer ride tomorrow, the recovery day will do your body a whole lot of good, and you'll be stronger for it on Sunday
... (nothing wrong with a little ride tomorrow if you REALLY can't stop yourself
).
Porridge
... it all depends on how you make it!
Mine is made with milk rather than water, with honey, a chopped banana and some cinnamon sprinkled over.
As for the water & salt version
(yes, I know that is a sacrilege for porridge purists
).
Alternatively, anything whole-meal or whole-flake, i.e. a muesli type cereal would be good, as it releases energy slowly, instead of giving you a quick sugar rush (like most Kelloggs type stuff with lots of added sugar & salt, ).
For snacks, I always take more than I think I need, including an emergency ration, just in case. The "extra" normally gets quite a few outings before it is consumed, but you never know when you (or a fellow cyclist) might need it
. What I am trying to say, you don't need to eat everything you take with you. We like bananas, muesli bars & flap jacks.
But watch out with the flap jacks, some aren't really snacks as they contain 400+ calories, which is the equivalent of a small meal! But they are great if you need a lot of fuel in a small package.
Lovely to see you so enthusiastic
T