Although it may not seem to have an immediate impact, one of the small changes you might consider is joining the Green Party. You can be a fully paid up member for around £10 per month. Membership means you get access to loads of useful information on the environmental movement (as well as all their other policy areas, such as social justice). You also get the chance to participate locally, vote on policy and people and go to their conference. And psychologically you get to feel like you are part of something that is part of the solution.