UK Contracting paid through Limited Company

[qbit]

Hi, I own a limited company. In order to raise funds I'm doing some contracting work personally (unrelated to the nature of the business) . Ideally all the money I earn I want to be put into the company. I know that contract workers often set up a company to get paid but can I use my existing company even though its unrelated work? This would of course mean that no tax would be paid (assuming no profits)?