how are you doing matt? Did you manage to make an appointment with the doc? If not, just wanted to let you know that you can get a simple blood sugar test done at your local pharmacy. I know Lloyds do it and possibly Boots, plus it's free!!
It may be nothing, but as the others have said excessive thirst is often the first sign of diabetes - the best thing to do is get it checked asap and then you can put your mind at rest. The test won't take a minute, it's a simple prick of the finger and a tiny sample of blood is taken. And you get the results in about 30 seconds so no waiting and no stress.
Your pharmacist will be able to advise you on what to do based on the result but if its normal I would urge you to make an appointment with your GP anyway to rule out anything serious.
Good Luck!