What is the usual commission (royalty) paid to a first time author of
fiction (a novel) in the UK by publishers?
What quantity of books sold makes a book a best seller in the UK?

You might find my answer to this similar question to be useful:

http://www.answers.google.com/answers/threadview?id=240711

A great deal depends upon the size of the publisher. Small houses pay
considerably less than the largest houses, and medium-sized publishers
pay something inbetween.

Kriswrite

Hi pinkfreud - your answer to similar question answers mine. (Can't
believe I did not notice the posting). Dont know what the deal is
since this is an answer to a previously asked question, but I do not
mind paying the fee at all, since I got what I asked for. Very
thorough answer, thanks.

To kriswrite - thank you for your comment.

Caribrob,

A friend and colleague has just called my attention to your comment.
It's too late for me to collect a fee, since the question has expired,
but I do appreciate your offer, and I am very glad to have been able
to provide some useful information.

~Pink