I asked a mates dad who works for local council as someone who gets in contractors (unfortunately not for WC) and he said £5 mill minimum before they even look at you, they also want book for 2 years, evidence of you being legit and reliable basically so that you wont let them down once you are given the job, quite a laborious process, but once you get in with them at least you know you will get what you asked for and the work will always be there....