Camping in the cold is ok IF you're set up for it properly, a few pointers for you in no particular order
1/ The tarp over the tent is a start, but if you can leave an air gap between the tent and the tarp it will be much better, cheap pool noodles are good for this
2/ A very good sleeping bag, if you can't afford a good 1 , go to "spotlight" and get several metres of "polar fleece" and cut it into lengths long enough to
completely cover you, head to toe.
3/ When you sit around the fire you can drape this same polar fleece over your chairs, keeps your back and bum warm
4/ Personal cleanliness is easy, 1 cup boiling water, 3 cups cold water in a small container and a face washer will give you a "pits and crutch" and a light wash every day.
5/ Thermal underwear is pretty cheap and effective, along with a "beenie" and waterproof gloves.
6/ A metal bucket with a few litres of water in it left beside the fire will give you lots of hot water for quick drinks, cuppasoup, noodles in a cup, etc and washing.
7/ Hot water bottles to pre heat your bed, re use the water tomorrow
8/ NEVER EVER FORGET THE BOOZE
Have a look at
www.myswag.org as well, an absolute "gold mine" of information there
cheers Keith