I just had an update and my BW11 has arrived in Tyne. They did say last week it was going to Grimsby.
VAG group as a whole have bundled as many cars as possible over into the UK to avoid the tariffs if yesterday went ahead in terms of no deal and import tariffs etc.
That mixed with the recent storms has apparently made ships unload in all over the UK, causing logistic nightmares and hence the slight delays from port to dealer. According to SEAT customer help