thank you for your advice!
if we had been invited to the whole day, the ceremony, the meal, and the bride had paid for my dinner in advance as is the norm, i would definitely still go, even if it meant having to borrow cash from my mum!! for the whole day, it would have been worth it.
and i am very much in the second tier - there was even a slightly awkward issue about the reply card - my invite was clearly evening only, but the reply card had a section for dietry requirements, which i filled in thinking the bride might have been planning a buffet or something - when she recieved it she emailed me saying she was so embarressed but some of the invites had been incorrectly printed and she just wanted to check that my invite had been for the evening only, not the meal; she was very apologetic. but i am definitely a second tier guest.
just to be clear i have no issue with that at all! We only meet up a couple of times a year for lunch with L, and although we have all known each other for many years i think these days there are many many more people who you see more than twice a year and they should definitely take priority!
Thanks for listening, everyone, you are ace! xx