Surely access is access, it's either been given or not. Clause 43.4 requires the Employer to give "access to and use of a part of the works" and it doesn't sound like they have, they have removed Plant and Materials from the works. Regardless as to the fact that it's a secure facility they still need to comply with the contract. Presumably there is a contractor with responsibility for maintaining the lifts at regular frequencies who is given access so there's no difference in principle from this.
Unfortunately, this all said and done, if this is the course of action they have chosen, despite the fact they are in breach of contract for preventing access, if they assess an amount and you disagree, the parties only recourse to resolve this is through adjudication. Inevitably neither party will want this so a commercial settlement would be more preferable for both.
Unfortunately, this all said and done, if this is the course of action they have chosen, despite the fact they are in breach of contract for preventing access, if they assess an amount and you disagree, the parties only recourse to resolve this is through adjudication. Inevitably neither party will want this so a commercial settlement would be more preferable for both.