The regulator, Ofgem, reviews energy prices every 3 months. The prices are governed by previous weeks and so, just as we pay our bills in arrears at the end of each month, the prices reflect the costs in the previous weeks.
The wholesale market starts to buy in what they think is needed to take the Northern Hemisphere through the autumn and winter – that is without being able to know in advance what the weather will be like. This makes pricing competitive.
Take a look at moneyhelper.org.uk if you are a vulnerable household.
You can pay by direct debit monthly in arrears paying for exactly what you have used. Please remember that you have to consider the higher bills in the winter but during the summer months your bills will be lower.