Brexit means Brexit
But what does that actually mean?
The question asked only mentioned the EU, it made no mention of any other European organisation.
Since originally joining the then EEC involved leaving the EFTA, a reasonable interpretation would be rejoining the EFTA, which would be a means to remain in the EEA.
If we remain in the EEA then it is pretty much business as usual (except for farmers, fishermen and UK based EU funded projects, but the latter .)
Leaving the EEA is what would make our economy go TITSUP.
I have also noticed a lot of post referendum promises that would seem to be impossible without remaining in the EEA (some could alternatively be met by the breakup of the UK).
The NI-Eire border being the most obvious one. (If the UK left the EEA it would become a customs border, because there would be no free trade agreement, so how could it be completely open? i.e passports won't be needed, but goods would need to be checked.)
Of course it could mean the whole UK leaves united or not at all. (And to be pedantic, Britain only refers to England, Scotland and Wales. And even more pedantically, it can mean simply England and Wales, i.e if it is not used as an abbreviation for Great Britain.)