I agree, it is complicated, and a bit of a minefield currently.
Stick to suppliers that are registered with HMRC and take the VAT at source and you should be okay. Otherwise, you are under the same rules as imports from RoW - VAT, plus import duties for items over £135, plus any handling fees.
As for whether you escape any import fees, I guess the same sort of regime will apply that already exists for RoW - if it's delivered by RM, it's pot luck as only a minority are checked. If it's delivered by a courier, virtually everything goes through customs and get caught.
edit: I'm not even sure about RM items escaping fees now, things are being certainly being delayed, so evreything could be going through the mincer.