Some nice ones in here. My favourite might be "absolute parcel." I've heard Brits and Aussies both call someone a muppet, but I'm not sure how to use it myself, even though people use that one stateside as they do "donut."
I'm posting this here because I first encountered "pillock" here. It was none other than Sean Mac making the required dig at Gary Numan. I also like "unit" and "absolute unit."
to clarify by exemplum
BozzoPooh blah blah blah & a collection of muppets
Just dawned on me how a franchise name like Mr. Donut might be funny to a visiting English person.
"Meet the 'Misters*' who make Mister DONUT better because 'We put our heart in it!' " Mister Donut Franchise Advertising, 1965
Anyway . . . carry on.