You can contact your applicable DNOs flexibility team directly;
Midlands, South West and Wales please contact Western Power Distibution
North East, Yorkshire and Northern Lincolnshire please contact Northern Powergrid
Central and Southern Scotland, North Wales, Merseyside, Cheshire and North Shropshire please contact SP Energy Networks
Northern Scotland and Central Southern England please contact Scottish and Southern Electricity Networks
North West England please contact Electricity North West.