"Dutch Courage" is a concept thought up by drunks.
While it may have been of some advantage to the likes of Vikings going into battle with clubs & axes & suchlike, it does no good in alleviating a state of nervousness, particularly where any kind of skill is required. It will only accentuate the nervousness.

Megan L's mum said a mouthful.

There are many fallacies regarding booze.
It will not cool you on a hot day, it actually makes you hotter.
Alcohol is a depressant. While you may get momentarily cheery with the loss of inhibition it affords, it will not raise your spirits, but dampen them.

Brucie also said a mouthful "If ya think ya got a problem, maybe ya do".

My credentials? Thirty years of hands-on research which ended when my first child was born.

John