If a 'bespoke' item, In other words, custom made, the rules are different from 'off the shelf' models, where that can just sell it to the next person who orders one.
I though 'late delivery' as a reason for cancellation only applied if more than 28 days. As they got the order on 2nd, and 28 days later is the 30th, late del might not be the right reason to cite for cancelling. But the 7 day cooling off period for distance selling might be the reason to give. But as said, this is not the case if 'bespoke'
Over to the rest for a much more accurate interpretation of these laws.