UK Local Election 5 May 2011?

After the General election, parents received some forms I believe from the electoral commission I believe, and it was a form I think for registering "persons in household 16 and over", I believe this is registering for the next general election. Now I have been added this year, will I be able to vote in the local elections on the 5th May 2011, or will it be effective of the 2015 elections, or when I become 18 in May 2012?