Off you go then and arrange all the trades at exactly the correct time.
It is really easy to do this and save your self some money but please give a
qualified report when the job is finished on exactly how much you saved and
how easy it was to get all the different trades to combine and work
together.

I find as a building contractor that yes I do put a percentage on other
peoples work but what people dont realise is who pays for the general skips
to clear the general rubbish, say the packing from the boiler unit, the off
cuts from the plasterboard, the odds and ends of mortar over. Oh you are
going to provide that OK. What about the phone calls liasing and programming
the works and trades. The extra cost to the electrician because the
carpenter had not finished a stud wall, The VAT collection and payment. The
Brickie walking off because you forgot to get the cement etc.

A quality contractor does not recieve a "BUNG" as you put it he just adds
whatever percentage he wants on the sub-contractor. It is down to you to
obtain several quotations on a drawing and specification from several
quality contractors. Off Course go to Old Hopalong Cassidy down the road and
get a really cheap price and then wait to put the work right yourself later.

Let us all know how you get on please