If your response to a campaigner for a cause you largely agree with is to call them a hypocrite because you can point out one or two things that they aren't doing in their personal lives to contribute to said cause even though they alone make a negligible difference, then you are a part of the problem. It's like when all those angry, balding 50 year old men saw a picture of Greta Thunberg on a plane once and decided that was sufficient evidence to invalidate everything she's ever said or campaigned for.
Insulating homes in Britain would make a large, positive difference. If it was cheap to do, the government would probably just do it, even the Tories. It's not an unreasonable demand from that campaign group. However, as others have said, with both these guys and Extinction Rebellion, their methods are just the absolute worst way to get the public behind them. ER have some particularly extreme idiots in their group who want to "bring down capitalism, man" and stuff like that but my understanding is that they're an environmentalist group who want to slow down climate change. The public broadly agree with taking action to prevent climate change yet Extinction Rebellion have a net -60 or so approval rating with the public because of their blocking of roads and preventing people from going about their lives. It might seem necessary but it's counter productive to their cause.
The Insulate Britain guy is a moron as well. He was on GMB last week and he stormed off stage after being asked simple questions and looked to be one bad sandwich order away from a mental breakdown. If you want to convince people to get on your side then you can't be picking people like that to rally behind as the face of your movement.
The problem is with these groups is that they all get together in this echo chamber, wind each other up about how much the world is against them, end up radicalising themselves and completely losing touch with the people they need to convince to support them before they go and make their case to the public.
The Greenpeace Downing Street advert (look it up) from a couple of months ago was a good example of how to go about these things. It was powerful without disrupting anyone's day to day life so when it got them trending on social media platforms people saw the British government portrayed in a negative light for not taking enough action rather than the campaigners themselves.