Pre-EU i worked for a company that rented professional audio equipment. I regularly took a >£100,000 gadget to Holland and this is how it worked.
In Harwich dock I had to go to five different porta-cabins and stand at a window in the rain while getting my papers stamped.
On the Dutch side they had everything in one warm building with showers and coffee machines. On one trip some jumped up official in Harwich forced me to alter the paperwork which meant that arriving in Hook van Holland they asked me for, IIRC, one million guilders in VAT! I had to take the next ferry back to Harwich :(
Is this how Brexit is going to be? One total fuck-up when trying to move goods around Europe!!