Here are a few crazy ideas:
A devalued pound may make exports more attractive.
Whilst a devalued pound may also make imports less attractive the U.K. consumer may instead plump for acquiring home produced goods and services.
An independent U.K. can remove tariffs on certain goods or services to make them more or less competitive.
A devalued pound could lead to an increase in interest rates. Though not popular with everyone - so careful management required - this may attract inward investment into the U.K.
We can award major construction or development contracts to U.K. companies rather than have to perhaps tender these across the EU.
You can pick any number of favourite sectors to which you might want to apply some of this **** in the same way that I can.