If you are confident that the new equipment you have is safe to use then go ahead and do so; It is generally accepted that new equipment is safe to use as it should have been tested by the manufacturer, but it is possible it got damaged in transit, or that it is not a genuine UK standard appliance – there are plenty of them on the market.
Assuming the appliance is genuine, complete the manufacturers warranty card included or register it online so you are notified of any issues that arise.
When we next come to test the rest of the equipment we will test the newer kit too. However if more than a year is to pass before our next visit it may be worth getting us in to check the newer kit when it’s a year old.
Whatever decision you make ensure it is an informed one and you are completely sure; as if there is an accident you may be held accountable.