Membership of the EEA provides both:
http://www.europarl.europa.eu/atyourservice/en/displayFtu.ht...
"The purpose of the European Economic Area (EEA) is to extend the EU’s internal market to countries in the European Free Trade Area (EFTA). These countries either do not wish to join the EU or have not yet done so."
"The EEA incorporates the four freedoms of the internal market (free movement of goods, people, services and capital)"
Which is basically what the people of the UK chose in 1975 with the EEC, before it grew into the EU.
That's assuming that it remains just as easy to do so, which seems unlikely given immigration was part of what was driving the leave vote. Even if it is still easier in absolute terms for someone in the EU to work in the UK than the US, the lowered differential could have pretty negative effects on the market for high-demand jobs.