I've had a few landrovers over the years and own a disco now.
I'am not a member of the disco club so cannot comment on them.
In general I've found many of these "Owners clubs" poor value for money you spend £20-£35 pa get a few odd news letters over the year invited to one greenlane half way across the country. Hardy any threads or posts on the forum, and negative comments quickly deleted. Often run by the founder and his family over the last 15 years, and with no access to other national members unable to vote him out. As for discounts find only relate to tyres at RPI prices and insurance is often cheaper if you shop about. Nor do I like pay first see later, let guests see the forum but only members
participate some clubs do this.
Use forums like these, there are several more about, look for members who belong to clubs which are active now, search there websites out and see what they are up to. Forums and the internet seem to have changed everything, I can roughly go laning or play day sites any time of the year by picking up threads early in the week. As for advice on maintence look for old threads some of the advice is excellent (better than the manuals) and free.
As for insurance had a series and found though a forum someone who was same age, similar occupation, same area, same vechicle, yet charged £15 cheaper when I inquired why told 10% extra handling fee going though a club.