The government has promised Britain will radically reduce carbon emissions – to achieve net-zero emissions by 2050. To get there, we'll need to make big changes to the way we live - to our homes, how we travel, and what we eat - but how much difference will these changes really make? With the help of a family in Nottingham, Justin Rowlatt finds out what are the most important things we can do and asks what the government is doing to encourage us to change the way we live.