A consumer can ask for a change of meter (or a reprogramming) once-a-year free of charge; I Suggest that you contact the service provider to change the meter and then look for a supplier. We did just this and now use “iSupply”. The source of meter will not be the Co-op but will be the major provider where you live. EDF provide this service in the South West of England (for example).
Timing for hot water (and other devices) on a separate meter is not necessary these days as cheap digital timers with battery backup allow you to set up many discrete on/off periods from a constantly “on” supply. You can use hot water on the main ring with a 7 day programmable timer like this one… [from Wilko]; in the event of a supply interruption the battery keeps the clock and timers alive also allows the use on a “night rate” supply without losing on/off timing.