We’ve only ever been invited as day guests so not sure about etiquette for evening guests. We know the groom as he is OH’s old school friend. They haven’t provided a gift list. Was thinking cash- but how much? We are really scrimping at the moment as we are trying to get a deposit together. I’ve bought nothing for myself for a few months! Would £30 from us both seem very stingy? Maybe £40? Thanks in advanced!