Upon arrival at a UK port-of-entry you will need to show your passport or identity card and go through the EU/EEA queue if arriving at a British port or airport. You may travel to the UK with your immediate family (spouse, children, dependent relatives if you are not on student status, and non-EU unmarried partners if they meet immigration regulations). If any of your family is not an EU/EEA national, then they must apply for an EEA family permit at the British Embassy in their home country before travelling to the UK.
You are a citizen of another EU new member country (as above) and you have been working in the UK legally for at least 12 months without a break. This is possible as of 1 May 2005; or
You are working as a self-employed person in the UK (in which case you must register with Inland Revenue as soon as you arrive in the UK); or