Plenty of foreign language teachers come from abroad to teach, so I don't think there's any lawful impediment, and you shouldn't have too much difficulty getting a job provided you're sufficiently qualified. Provided your command of English and the languages you wish to teach is up to a sufficient standard then there'll be a demand for your services. If you've studied in the UK then that should be a great help too. Doing some training in education or some part-time work as a substitute could also be useful to you, since experience counts when making a job application. Like Psy said, since you're from an EU country you shouldn't have any trouble getting a visa, so I wouldn't worry about the legal side of things and start thinking about how best to get into the teaching profession.

Best of luck with whatever you decide to do.