The scheme to get a 50% discount (up to £10) when you eat in at restaurants that are registered with the Eat Out to Help Out Scheme runs every Monday, Tuesday and Wednesday until 31 August 2020.
You don’t need a voucher; the rules and how to find the participating restaurants, cafes etc is all here on the Government Eat Out to Help Out Scheme web page.
Station to Station has helpfully listed the participating West Norwood town centre restaurants, cafes etc here in their Business Directory.