Moaning about the weather in the U.K. is a national pastime due to its fickle nature, so I think we can count that as a national trait.
I think the U.K. , England particularly, is a land of moderation in most things, so when Brits move abroad to a place of extremes in weather, food, speech etc. it's more of a shock and hence there's a bit more moaning.
Brits are also more ironic in their speech so phrases like "you'll be the death of me" or "we'll be waiting here forever" whilst meant jokingly can be misunderstood and taken literally.
Over the years I've learnt to complain sparingly in front of Thais.
By the the way, if you've been with a group of tipsy Thai women you'll know just how much they like to moan about other women. : )