Indeed, and everyone saying it's the British customs fault it isn't.
The French authorise onward travel of goods and let them board. Not the UK.
The French are wanting the correct paperwork, but the Netherlands have just said they have temporarily stopped customs paperwork for aid for Ukraine. So all you have to do now, is UK - Netherlands with your goods.
Ever wondered why the French never just let a load of refugees in Calais board a boat, be easier for them wouldn't it, but no the UK are in charge of onward travel in Calais to British soil and vice versa.