If anyone turns up at a club as a visitor/guest for a shoot do not be under any misapprehension that you would have much in the way of cover. Think of it as 3rd party i.e. there is no personal injury or loss cover on most policies. Your gear is not covered by the site if you trip over a blade of grass and stuff the rifle in to the ground and snap the scope in two. If you fall on top of a spectator then maybe the spectator has a claim against the club but I doubt it.
If you worry about cover get a personal policy (e.g. BASC or NSRA individual memberships) and then you are covered for traveling to an event, hunting rats, plinking, going to your zero range when there is no Club event, etc. Read the fine print but Club insurance is primarily for a Club's civil liabilities and property and liability incurred by actions of its Members.
Insurance companies make their profits from false assumptions. The BFTA card identifies your BFTA number and Club you belong to and that the Club had insurance cover at the time of requesting the cards.
Also note that if anyone offers training or coaching they will not be covered by the standard NSRA Club policy and they must have Individual Membership Cover and belong to a Club which has affiliated with NSRA. Quite how "training and coaching" is defined and what the difference is between that and friendly advice is something for the lawyers.
BFTA is seeking clarification on some of these items (probably at the next AGM) but there are many who may believe their cover is more than it actually is.