The Palestinian protest isn't even taking place on the Sunday. It's on Saturday and it's taking place a few hours after the 2 minute silence on the Saturday.
What we're seeing is the British government (and a few other factions) trying to whip up some nationalism, and using jingoistic tropes to make what have been largely peaceful protests into something a bit more fractious.
There's also been a few 'call to arms' from far right groups (EDL, and another one called 'Football Lads Alliance') to defend the cenotaph on the Sunday (again, there's no protest on the Sunday), but knowing their ilk, they'll turn up on the Saturday as well to provoke.
Edit: And yes, I'll most likely be attending (on the Saturday).