"James
Child, here's a valuable life lesson; stuff like karting is too expensive to constantly do, so in the immortal words of Jenson Button: 'Pick up a tennis racket or a football, it's technically better than going into an expensive sport with only 20 competitors which you probably wont be one of, and the rules dont change every time the sun rises.'
Seen it, done it, been there.
My brother was fairly good in karts and even won a few trophies in the UK about 25 years ago but it wasn't cheap to participate. Our parents weren't very wealthly and he wasn't the fastest so there was no 'sugar daddy' sponsor to help pay for it all. It lastest three years before he had to give it all up due to the cost and he is now a policeman.
I advise you find a friend who can secretly take you to a couple of cheap arrive-and-drive events at a local track and if you blitz the opposition you'll know you have the knack and you'll get the attention of the circuit owners. If not then you can go and buy an X-Box and a copy of Forza and you will at least still have some money left in a few years time.