If it was just the one email, I'd be annoyed too, as when you have multiple DC at multiple schools sometimes things can get missed. Thats just life, we are not all admin guru's and there have been things in the past I have missed, but luckily the 4 schools my 5 dc attend now all send out reminders for everything, so stuff gets picked up then if its been missed.
For a whole year trip, for a whole day I am surprised this wasn't communicated more than once tbh. I bet they managed to communicate the buying of easter raffle tickets or the £1 you need to bring in for non uniform day multiple times though. Those things are hammered home.
For mine there are multiple places these things appear too, sometimes in letter form sent home, sometimes email, sometimes in the weekly newsletter, sometimes in the app thingy, sometimes its been on a board just outside the classroom for the youngest and no where else, and as I don't drop and collect dc those ones are always missed.
Unfortunately, its too late to do anything about it but I would just mention to the school you are disappointed you missed the (one) email they sent about it, and maybe another time they will ensure they send a couple. Emails do get lost, get put in junk sometimes, you won't be the only parent who missed it i'm sure.
We do also have a group facebook page where its just parents for the youngest dc school, and we have a fantastic mum on there who is a sahm and totally on top of all the school admin! And she always posts a summary of the important stuff we all need to know. Us working mums think she is god. She's definitely getting a bottle of gin again for christmas!