2.There are two main types of tariffs – Variable rate tariffs and fixed-rate tariffs.
In fixed-rate tariffs, your energy unit price is fixed for 12 to 24 months. In variable tariff, energy unit price fluctuates with the market price.
In general, fixed-rate tariffs are cheaper. But select what is cheaper in your quotation. Some fixed priced tariffs come with an exit fee if you leave before your contract period ends (10-50 pounds).