Andy’s agent for cartoon work is Gordon Wise at Curtis Brown. You can contact him via this page..
His agent for scriptwriting is Lily Williams at Curtis Brown. You can contact her via this page..
Andy also has a publicly available email where you can contact him directly. But before you do, please look at this FAQ post to see if your question is covered there. In particular – if you’re about to send me an unsolicited sample of your writing and you’d like my opinion on it, please first read the answer to the third FAQ, “I’ve got a script – can you read it and give me some feedback?”
If the answer to your question really isn’t in any of the FAQs, get in touch using firstname.lastname@example.org and a link to that is here.