OK, they don't stock it at the moment and I don't see any stores with it. However, I found it in France on eBay under the original name of Blue Ridge Models, but the shipping is the same as the three resin parts! Please check the item number from your own browser as shipping may be different to the UK:
U boot boat type vii 1/72 upper pressure hull hull pressure no blue ridge yanke | eBay
My recommendation? Since Blue Ridge seems to refer to the Blue Ridge Mounts, Yankee to the US civil dispute of the 19th century, it may be that the molds to cast new sets are down South (as we say in the US).
Online Hobby Store | Modelling Kits Hobby Shop | Model Kits (freetimehobbies.com)
I've asked my Parisian friend to inquire at the shop.
Regards,