Good will still be shipped in and out. There will be regulations that needs to be adhered to, taxes charged and the likes. However, instead of giving more in EU than they receive they will be able to get what they give or even get more than they given with other trade deals. This is Great for Britain. No one is saying it's going to be easy, no one is saying it's going to be a walk in the park.
There will be job cuts, there will be negative growth for a period. However, eventually with Britain in full control, they will be able to direct their own destination and not be limited to EU limitations.
Please stop painting this doom and gloom picture. Truck drivers there will be, probably a couple will lose their jobs in the short run, however there will be much more jobs available once the dust settles.