I get you, OP, I'm offended on a gender and a 'restrictive view of Britain' perspective (not to mention the spelling mistake!) and I'd be disappointed if my kids came home from school with that too.
I may have missed this but is it an official school thing or a PTA thing? I've found that sadly the PTAs I've known over the years are - despite efforts, time, cake making skills etc, are not exactly on the ball to say the least when it comes to efficiency, common sense, diversity awareness or indeed good old political correctness.
If it's the school then they should bloody well know better than to produce that kind of tosh.
I'd speak to / email the head in the first instance and see what their view on the matter is. Chances are it slipped through the net but they ought to be seen to be apologising and removing the rather prescriptive food and clothing requirements.
In the meantime, dress a boy as Emmeline Pankhurst and a girl as Isambard Kingdom Brunel or someone (you get the idea!) and send them in with a range of dishes like samosas, spring rolls, egg fried rice etc. Revolution from within!
So YANBU to be irked by this.
Good luck - would be interested to know how it works out.