I've been twice but I tend to cherry pick the stands a bit and do a mix of things I know I can hit for a confidence boost and mix it in with stands I'm not so good at. It's always a school day on the range. @wymberley I'm also shooting an old sxs at the minute and it's definitely more challenging (but part of the fun)!
If you can face the drive, I'd really recommend North Devon for a nice round of targets and they regularly take beginners round there (it's all caddied by the owners currently). Alternatively if you find yourself down this way on a weekend, West Tapps (has a website)