The lack of energies is part of why May's trying to put Article 50 off into the long grass for as long as she can, I think. The time gained is nowhere near enough for substantive trade deals to be put through, but it helps her get at least minor things like declarations of interest as a starting point and a domestic political tool.
My feeling further is that the gesture of eventually invoking Article 50 will be worth far more to the Tories than your focus on the genuine practicalities of the matter, certainly in the short term. The 2020 election will be spun in terms of "we took the country out of Europe only nine months ago, like you wanted - now reward us for that, and let us deliver on all these totally meaningful preliminary prefatory talks we held in the U.N. cafeteria during a coffee break which definitely make up for the loss of easy EU trade." And politicians are famously bad at looking more than one election into the future.
Maybe in the 2025 election, voters will punish the Conservatives for the fact that post-Brexit Britain hasn't freed up a billion working-class jobs and lowered taxes and funded the NHS and whatever else leaving the EU was magically supposed to do. But no-one can deliver on that, whether they go for the neoliberal line or try to be protectionist interventionists. The Tories know that and so will make a couple of token gestures while continuing to do what they think best, which is to expand global trade with Britain as best they can. Remember that even the Conservative MPs weren't in favour of Brexit: they know this is going to be painful, and that there's only so much alleviation that can possibly be put in place. Nevertheless, regardless of how thoroughly neoliberal, Eurosceptic, and globalist they are, they're certainly the most neoliberal, Eurosceptic, and globalist party outside single-issue UKIP - and that translates into more of a forward drive than scrabbling to make Brexit as minimal as possible (which would be arguably the most sensible choice and certainly what I'd expect out of, say, a sane Labour government faced with this) or reverting to self-defeating trade barriers.