Hi, I have just admitted I am compulsive liar I need help! I am not sure where to go for advice, my partner suggests my GP.

You need to go see a phychiatrist or phychologist. The GP isn't really going to be of much help to you... other than maybe to give you a recommendation to a specialist you should see. A good Psych Dr can determine the degree of your disorder. Whether it's something you do just to get you out of certain situations? or if it's a compulsion, or a pathelogical disorder.