No matter which way you vote on May 22nd, it won't affect the euro. The single European currency was approved in 1992, when we voted on the Maastricht Treaty. There has been a lot talk about it recently, because at last we have come to the big decision: who will be in, which was agreed in Brussels on May 2nd.
The other big question - when will it begin? - was answered in 1996, when EU governments decided not to start in 1997, but to wait until January 1st, 1999. The changeover will take three years, and you should start to get euro notes and coins in your pockets and purses in early 2002. A big programme of public information and information for schools will start quite soon.