Am I entitled to remove materials or equipment from site which has not been paid for?

You have to be very careful about doing this.

First, the general rule is that once materials and equipment have become affixed to property title transfers to the owner of the property.  There are some exceptions to this rule, but there is a risk that you will be guilty of theft and what is known of the tort of conversion and trespass if you do remove materials or equipment attached to a building or property.

Secondly, check the terms of your contract with Carillion as to whether title to materials and equipment delivered to site but not yet incorporated into it has passed.  Often, main contractors’ bespoke contract terms provide that title passes on delivery to site, rather than upon payment.