Hi Sculley. Really pleased you had a go on the range at Highclere - its a great way to catch the bug and that's why Daystate and the Cambridge HFT club put them on at the shows.
You can set yourself up with full kit if you select s/hand purchases carefully, for about £600 pounds. That would get you an accurate enough rifle, reasonable scope, and a dive cylinder.
If you start taking it really seriously and want to compete at the very top level then you are looking at £2,000+.