A thought.
If the UK votes to exit the EU then Scotland will be forced out, like it or not.
Should the Scots then get independence they would have to re-apply, if they want the Euro. That currency is only available to EU Members.
I suppose they could always adopt the US$, like Zimbabwe.....
Personally I have always been in favour of a single currency world wide. We would then have security in pricing of goods and services world over. It would stop the greedy speculators that, in some cases, are powerful enough to change currency values and become wealthy without creating anything of value. Governments would then be forced to take measures, other than currency control, to manage their domestic economies, that in itself would be a good thing.
When I travel or buy goods in the Euro zone I know exactly what it is costing me. By comparison, for me with my income in Australia, and residence in Europe, travel or purchases in the UK have increased in cost by 15% in the last 12 months.
That favours imports into the UK, and hinders exports: all bad for UK manufacturing and employment.