I'm not a porridge fan - I usually have muesli for breakfast, ride or no ride.
Personally, I find that my energy levels are linked to how balanced my diet is rather than focussing on the science of protein shakes etc. If I've not been eating much fruit and veg and not had enough water to drink the day or two before a ride, long or short, I really feel it in my legs.
I should point out that although I clock up a decent mileage, it's not done at a particularly fast pace (10-12mph) so my experience is worthless if you're built for speed, not comfort.