The Trussell Trust, which has a network of food banks across the UK, has this useful online resource which plots local food banks on a map, along with details about how to donate to them and contact details: https://www.trusselltrust.org/coronavirus-food-banks/
Its important to contact the foodbank in advance of referring/signposting residents as the service, frequency or supply chhanges quite frequently. Many areas are also setting up tempoary sites for donations and collections