Crikey- a euphemism for 'Christ keep me'.
Blimey- a euphamism for 'God blind me'.
( The full expression being 'Gor Blimey'.)
Both used originally by the God fearing to avoid directly taking the Lord's name in vain, but without uttering actual expletives.
You could also try-
Fiddlesticks.
Gordon Bennett!
Flipping heck!
Blinking.
Blooming Ada, or my favourite,
Well! I'll go to the foot of our stairs!
Alan
