I'm a member of the RMT. My husband is a member of the CWU. I'm in the public sector, just, TfL. DH is in Royal Mail, a postal worker. We both have disputes with our employers.
It really is a race to the bottom out there. I stand to lose 600 colleagues. So if you need help, either with your travel costs, with finding a step-free route, with needing an arm to take you to the platform...you will be out of luck in the future. In the outlying stations, there's rumours of putting one member of staff mobile between 2-3 stations. If you are disabled, or a victim of crime, how are you going to get the help you need?
DH has had a 2% pay offer imposed on him. If the union agree to a whole load of unpalatable conditions he might get 5.5%. But inflation is running at 9-11% so even though my wage has increased with RPI, his hasn't, so overall our income combined will reduce in real terms, regardless. Meanwhile Royal Mail paid its CEO £140k in bonuses and handed out the majority of it profits to its shareholders.
It's not just our jobs. It's everywhere. Telecommunications, Courier services, Amazon, education, cleaning services, barristers, Deliveroo, council services, shipping...people are losing money, they can't pay the bills, the burden on food banks grow, the companies make redundancies to cut costs...yet the corporations are taking it in, to the tune of billions. Look at British Gas's recent profits. It's obscene.
There are general unions out there...try the GMB as a start. But yes, go to the link OP posted at the TUC site, and join a union. Also, look up the Enough is Enough campaign on Twitter led by the unions to try and change things for the better. It won't solve all the problems but it's a start.