I think Trent is right, that it's actually impossible to articulate a clear view of Brexit, since so many incompatible things are being subsumed into it. It's clearly impossible for companies to stop exporting and importing with the EU, but as a third country, we can expect some kind of non-tariff barriers. These could become severe, if there are checks on lorries, cargoes, drivers, provenance, and so on. If each lorry takes a few minutes, result, chaos at Dover, or standstill.
So they are trying to find a way round this, without staying in the single market. Hence Mrs May's talk of frictionless trade, but nobody can really describe this, without being in the EEA, and in addition, why would the EU accept it? It does sound like leaving the gym, but asking to use the pool every morning.
The Ultras are supposedly looking for a crash out, not a deal, resulting in tax haven status, with heavy deregulation. This is another right wing fantasy, and one result might be cancelling social services.
Maybe in the end, there will be a deal, but they are leaving it very late. They have got into something that nobody understands, and nobody can find a way out of. Of course, the EEA provides a solution, but that has now become ideologically unpleasant for the right wing.