You need to strengthen your position when it comes time to submit your Payment Claim by keeping a Construction Site Diary daily!
Each day you deal with with so many people and organisations at many and varied levels. Each interaction can be potentially costly if not handled well or potentially beneficial if all goes well. You need to keep a written record of all these interactions.
Consider a Construction Site Diary as insurance and hope you never need to make a claim with it.
When relationships go off the rails well kept records of events, meetings, correspondence, requests, instructions, quotations, progress, quality, accuracy, etc.. become invaluable.
A comprehensive, accurate record may help you and another party resolve a dispute before it escalates. Being able to sit down and review your Construction Site Diary with the Project Principal, your client or another sub contractor or the like will help each other align and find common ground for a fair and equitable resolution.
If a resolution is not possible and you find yourself making a Security Of Payment Act Claim and then an Adjudication Application or applying for a Statutory Demand in a Court then this record that you have kept daily will carry a lot of weight with an Adjudicator, Magistrate or Judge when they are seeking to understand the truth of the situation.