Hiya,
I am a veteran student, been one for the past 5 years!!
Urm though not the best to ask regarding the subject of eating, as Im veggie, so i eat a lot of vegetables, pulses etc!! Though I to have small food budget, and a love of nice food, cant be doing all this tesco value malarkey!! The best way I have found to make money last, and to make sure I buy sensible food, is to plan it! I know it sounds incredibly dull, but it works. Write up a rough plan on the meals youll be eating, try and pick things that share some of the same ingredients so you dont end up throwing ingredients away! Then buy just whats on the list when you go, so you dont end up buying impulse purchases of things you dont really need. That always works for me, the writing the list and sticking to it, means i dont spend a lot, buy junk, or throw half the stuff away, its all what i need!
Another well known food shopping trick, and it really does work. Is go shopping after youve just eaten. Coz your full yo dont get random craving for things and buy junk! Honestly it does work, or for me it does.
As for fitting running in, im not that serious a runner, I do it for fun, so Im not any strict schedule for anything, which makes stuff easier it gets fitted in when there is time! Though if your playing rugby, the training for that will be helping to keep the fitness up. Though I know it can be so hard to fit in everything inbetween work, deadlines, socialising, and on that I have no advice, Im crap at it! And i tend to justify my running time as a "good thing" coz it relaxes me so much, I kid myself it makes me more efficient!
But I do truely hate running in the dark and the cold, I cant make myself do it. So Ive taken the rather lazy option of joining a gym for the winter months, which I know sounds an additional stress on finances, but youd be suprised how reasonable it can work out. Loads of chains do a reasonable student discount, my gym also has the advantages of having a "running club" a few evenings a week, which means theres someone there to bully me to get out to do some "real" running!