Through an unexpected series of connections I have been invited to the birthday party of an older lady who is turning 90. She is lovely and very sweet. The party will have her family that I don’t know very well who are posh and a real mixed bag (some are lovely and some are extremely rude/entitled) so it should be quite entertaining. This woman is very wealthy and lives in a mansion in Kensington but it’s still an at-home thing so casual in that sense. I’m used to birthday parties where I’m bringing cheap prosecco and crisps to a friend’s house. What should I bring in this situation??