What do you think of the idea of oil refineries being blockaded? Or those who invest in and profit from fossil fuels being targeted?
Depends on how etc. I think blockading of currently operating oil facilities is likely to be very difficult (number of entrances, safety concerns, how much comes in and out by road on a daily basis rather than pipes etc.) and it will also be met with a harsh response and likely poor publicity. They also would require a good number of people that would be willing to risk getting arrested, and for it to work they would likely need to do more than just lie in the way, even if they are locked on to stuff. Also obviously strongly single location focused, so people have to travel to do anything, so that would cut involvement/numbers down. And it'd be massive amounts of planning and resources for one day that could just end up an ineffective disaster.
E2A: The people that work there could do it, but that's being possible is a different topic unfortunately.
The financial stuff sounds better, but in reality it is again largely symbolic, and often just results in local bank branches being hit with a banner or something, or maybe the roads in City of London being blocked.
Off top of my head if I were to pick an area for a target I'd hit new any oil and gas exploration. Easy demand, no new oil or gas developments in the UK. Big rolling co-ordinated attacks across the country against anyone involved in them, so decentralized stuff against suppliers, etc. as well as central things possible.
I dunno though, I fully accept it's really difficult and people are trying.