Stuart
I had the same problem when I started and the best bet is to join a club. Members are usually ok with people trying out their guns, as it is unlikely you will be able to find a good selection even second hand in a shop. Only other option is to look on the web to see when places get them nearby in or if you are likely to be near Bisley they have a good selection of new ones together with some second hand ones in the shop.
Regards
Phil