Hi all, apologies for the out of date info on the SUI page, it has been updated now, unfortunately due to changes in the way the FFS process insurance for foreign organisations there has been a substantial increase in the price. The SUI is looking into alternative arrangements for next year but unfortunately didn't have time to deal with it before the 2020 season due to short notice.
In response to the initial query:
The SUI offers an upgrade facility for existing basic members to upgrade to full membership directly through the members area. If you have acquired BCA (or FFS) membership separately then you can get in touch with the SUI membership secretary and become an SUI member for our own direct membership fee of €20, proof of BCA membership WILL be requested for anyone applying through this route.
I am not sure what is meant by 'Club Insurance', even when a club handles BCA/SUI payments directly it would still result in the individual being insured personally, not the Club itself (Which would be covered by virtue of all members being insured.)
If you mean something like insurance for taking people on paid trips then you would instead be looking at some level of public indemnity similar to any adventure sports business (That EXPLICITLY covers caving, most will not) and would have to abide by all the regulations in that area.