The Mossie was pretty straight winged...and it did have a bomb bay. I would love to someday model the Cookie Mossie which had a bulged bomb bay to account for the 5000 lb Cookie High Density bomb....
The Beaufighter, which Tamiya also does wonderfully-- was also straight winged....but no bomb bay...it usually only carried a bomb on each wing.
As for RAF twin-engine medium bombers--
There was:
Armstrong Whitworth WHitley
Avro Manchester
Bristol Beaufort
Bristol Blenheim
Douglas Boston
Handley Hampden
Vickers-Armstrongs Wellington
Out of all of them-- the only one that looks sort of gull winged from the front profile is the Whitley. But I probably didn't list all of them....that's all I have in my book here....