When we have staff training the school often provides lunch and on parents nights (we have long ones from 3.30- 9) they usually get in some pizzas for us to have in a spare few minutes.
When we go out for end of term dos we all pay for ourselves.
We get given a free school Christmas dinner
but only if we go and help, serve meals, spread Christmas cheer etc.
The most recent survey of teachers hours showed that on average a full time teacher works 60 hours a week...
Directed time is 32.5 hours a week. (i.e. what we actually get paid for.)
As for all those school holidays-Many teachers work through the majority of these and we don't get paid for them either. 
I think £500 as a gesture of goodwill sounds like a nice idea.
That is of course if, with teachers leaving the profession in droves, there are any staff left to treat!