It's a big leap, and a lot of pressure with very little security. Part time it at first, and get a taste for living off deadlines and putting yourself out there. Freelancing in any form is difficult and much more time consuming than it initially appears, and it takes a lot of dedication and late nights to really make a living from it.
If you like drawing more than security, weekends, a credit rating worth talking about, for many people other-human-contact then go ahead, but it is definitely a precarious choice.
That being said, there are some fantastic jobs out there, and if you're the master of time management, self motivation and self promotion, you can do great things.