EEC Citizens have the right to live and work in the UK, known as excercising Treaty rights.

 You are entitled to vote in Local Elections and to vote for British MEP, but not in General Elections.

http://www.ind.homeoffice.gov.uk/applying/eeaeunationals

Citizens from the Commonwealth however have more rights than EEC Citizens in the UK. Commonwealth Citizens in the UK enjoy all UK civic rights, i.e. can vote on all elections including the General Elections, can stand for office, and can join the armed forces, Police. etc.