Thank you everyone for your guidance. I was baptised Catholic, but didn’t grow up going to church or anything, and I only made the decision to follow the faith properly a few months ago, and I don’t have any Catholic friends (or a family that practices properly, it seems). So things like this can be really confusing!
Unfortunately, it is also a reason for my family to not take me seriously, or to say that I am a hypocrite etc because I don’t take communion (because I haven’t yet completed the RCIA). But I feel it would be wrong for me to use my lack of initiation as an excuse - I have made the decision to become initiated, so I should follow the rules from now, not from some point in the future.
I think I will follow the advice of several of you, and cheerfully participate in the secular celebration, but abstain from meat, only eat a small meal, and go to a church service. The lunch is apparently at 12, so a 3pm service should be easy enough to get to. I’m not a minor, so I can drive myself there.
Thank you again.