The UK patent number is GB2353282
I think it expires in 2013.
As far as the US patent is concerned, from memory, I think Benitec was granted only an 18 month extension which means that it will expire 21 years after the date of the invention, which should be about 2016. Someone else may have a clearer recollection but it is all on the public record, so you can find the info online.