I'd agree that the 50 f1.8 is a nice, cheap low light lens, but agree with Duncan that it's worth using your kit lens to work out with 50mm will be the right focal length. If so then there's a 50 f1.8 up for sale on another forum for a good price -
http://www.ukbirdphotographers.net/f...hp?f=27&t=2756