I don't blame May too much for her stance to be honest. Politically she can't keep us in the EEA or EFTA because the people clearly voted for control on immigration and to do our own trade deals. She's in a difficult, if not impossible, position. Compare her to Corbyn right now and the difference is incredible.
As for the single market; I think ultimately it could prove quite costly. We're a strong country so we should be able to cope fine, but no doubt we would've been stronger in a market of 500+ million. I never like when EU leaders say no europe a la carte though, as if all 4 freedoms exist perfectly in the current state of the EU.
There will be opportunities to us that we'll have to take wisely. I was pretty upset directly after the referendum, heck I still am today, but we have to give it a chance. No point complaining forever, albeit complaining is very different to campaigning. If the Lid Dems get their shit together they may have my vote.