Yes, there are plenty. If you type the words 'UK cartoon companies' in a search engine you will find several examples. You can see one example here

If you are looking for any specific type of cartoon you will have to narrow your search. For example, are you looking for children's cartoons, the humorous cartoon one-off sketches that appear in newspapers and magazines, or something else? Are you interested in drawings that appear in print media or animations? As you can see, there are a lot of answers to your question: So you may like to try asking another question, with a bit more detail, and then you will probably get a more exact answer.

Cartoons and graphic art generally are now very big business in the UK and elsewhere, so whatever kind of graphic art you are interested in you will probably find a company that supplies it. If you have any very specific questions you could also try contacting a cartoon company and asking for further information.