Maybe only indirectly connected to our discussion on VAT, but if we had stayed in the Customs Union would VAT on private sales to/from the EU have been a non issue?
Leaving the Customs Union means we now have the freedom to lower import duties from the rest of the world, which is a good thing for UK consumers.
I must admit I was also unaware that 75% of customs duties the UK collected while it was part of the EU Customs Union were paid across to EU coffers. I guess I can see why the EU was pushing for us to remain in this - something new I've learned today!
In theory, I presume we could rejoin the Customs Union at any point if we wanted to eg Turkey is a member, I believe, (although prevented from joining the EU, itself, by France who don't want the free movement implications).
So if the costs of not being in the Customs Union outweigh the benefits, this should theoretically be relatively easily reversed down the line.