No point in going to the GP....by the time you get an appointment you will be better, though you may have come down with something else by then.
Also there's nowt the doc can do for flu or colds.
Best advice is to rest up, drink plenty of water to avoid dehydration(colds make you sweat more as your body works to fight them off so you need more fluid than you usually do.)
and take 1000mgs(? dose may be incorrect..at least 2 big vit c tablets each day, at different times and along with zinc is the best way) this can reduce the symptoms and duration of a cold by a third.
eucalyptus oil is great for making you be able to breathe better and a few drops in a bath is great for soothing muscle aches...
Hot honey and lemon drinks are comforting though pointless other than that, so have the sports lucozade type drinks instead as these have the sugars and salts you need if you have been off your food not drinking enough etc (also they are great for hangovers)