Most can't do it. And the way those that can will could be by cutting just about all discretionary spending - so no meals out, fewer take-aways, fewer trips to the cinema, fewer day trips to the seaside, fewer magazine subscriptions, maybe cut out away matches and so on. That means less overtime/extra hours at all those places you are no longer spending so those poor sods are earning less ( some may lose their jobs ) less tax being paid , less profits being made and so on and so on.
Throughout all this you will note the utility companies are getting that £400 pm per household thus swelling their coffers even more with a windfall they never expected and will not be used as any investment - there will be no more power generated by say wind to lower the price - no new reservoirs will be built and so on. Your real enemies are these allegedly privatised monopolies and the Govt who are their enablers.