Ok, To keep warm wrap up, but dont keep your place boiling, and wear tshirts and that indoors, no joke it keeps you warmer when you wrap up to go outside.
To get a job and meet people, I'd say get a job in a bar some where, it shouldn't to be to hard for a couple of reasons, England is binge drinking capital of europe, your in a city, so lots of pubs and lots of drinkers, and leeds is a Very Big uni city, It has two unis, students need to drink alot more than your average joe, fact, plus within the next month or so all the students will go home, so if you can't get a job in november, you'll be able to get one in december for sure.
Once you have your job you'll have more money coming in and you'll either meet people at work (even though most will be drunkards) and its usually the case that you'll go out for a few with the people you work with.
Keeping you costs down... well for food shopping remember your in a student town, so it should be cheaper in the right places, Go to Aldi, i love that place, Tesco and Asda are pretty cheap as well, as is morrisons, Make a shopping list before you go out, trust me it works, if you don't you'll go out for milk, fruit, cereal and bread, and come back with Pizza, drink, milk shake and chocolate and sundried tomatoes. as beergirl said get the very cheap label brands, if a deal is buy one get one half price, don't bother if you dont need two, if its buy one get one free and you can stick it a freezer then go for it. If you can't already LEARN TO COOK! its soooooo much cheaper cooking for yourself than buying ready meals, or things that are partialy ready, for example you can by a tin of pasta sauce, or you can get some tomatoe purie, some cream what ever meat and veg your having and make you own (frying pan - 10 - 25mins you have a shit hot meal for cheap)
to be honest i keep myself entertained by losing my sanity, but i can understand why thats not an appealing option for all, i find cooking and music generally keep me entertained - try dancing to some ska whilst chopping veg
, but mainly alcohol/climbing/kickboxing, but thats me not you.
for late trains..... get hold of some Jack Johnson....