I’m English and it sounds slightly off to my ear if somebody requests something and says thanks in the same sentence. To me, you thank somebody after they’ve done something. Making a request and immediately saying thanks is like presuming they’re definitely going to do it, which cancels out the whole pretend formality of requesting instead of commanding.

I know practically a canteen worker isn’t going to deny your request so it’s all unnecessary social nonsense but it’s funny spelling these tiny differences out.