With my old gas boiler I had the habit of heating the hot water tank most days for half an hour, which would last the day, that was costing around 52.5p on those days, that would be about 76p now.
With the new combi-boiler it costs under 14p at the new rates for enough hot water to shower and do the washing-up, it's a bit of an inconvenience not having a tank for hot water on tap during the day and having to wait the extra time for the hot water to travel from the boiler to the bathroom, but I've got used to washing my hands with cold water now, although that may change as we head into winter, and much colder water.