Well let's see... brits...
English:
-Wearers of tweed jackets and monacles
-Always polite, totally unexcitable and reserved
-Aren't getting any
-Have a fascination with horse-racing or hunting
-Avid tea-drinkers and biscuit dunkers
If you don't fit into this category then you have the other extreme...
The football hooligan.
Welsh:
-Where's Wales?
-Have improper thoughts about sheep.
Scottish:
Haggis, kilts and bagpipes.