I can sympathize with the worry about paperwork. That's why a lot of people are here teaching English illegally. Americans especially can't get work permits, but there are companies that want people with North American accents. Someone told me the other day that even if you try to do it legally, the chance you will get your paperwork back before you are ready to leave is slim.

If you have an internet based company in the UK, how would anyone ever know that you were working on it? And why would bringing money in from the UK cause problems? Isn't the ability to move around one of the benefits of being an EU citizen?