Join Up!
I have no idea what you value your time at, but say you like your free time as much as the national minimum wage. Then the annual fee buys about thirty hours of your time, and if you can honestly say you are going to spend that thirty hours a year or more, writing letters to the planners, government departments and nimby's etc, then you have a case for skipping the membership.
If you're not going to spend that time protecting the future of flying, and not going to pay anybody else to do it, then don't winge when you can't fly anymore 'cos theres nowhere to fly from, or the only place will charge you 500 quid for a landing & mandatory handling
puts on tin hat and nomex suit!