I dont think you ever will to many people and groups, websites etc. The only you will do that is for every group, prepper, blog website and whatever to join a national website like american preppers and then have seperate groups and websites but all work from one main site.
I love the idea of being able to identify other preppers/survivalists.
I think it could be do-able.
The American preppers/survivalists go by certain motos.
I think we are best starting with "S.UK Prpr" It would be clear that Prpr would mean prepper. If not, then Prepr would work. Then, as NR had with his original idea, having the tag of S.UK to hold us to a single site.
Unless someone makes a website with a 'National UK Prepper' symbol. A website like introtoprepping and another called introtosurvivalist and have the same symbol for that. Have the website as an open resource, then link in the other forums through that site. That would be the best way to unite everyone under one symbol.