I finally bit the bullet a few months ago. I started with a #1 (1/8"), and went down to a #0 (1/16") when I lost the #1 guard. You can always go shorter, but it doesn't take long for mistakes to grow out at that length. Make sure you shave the back of your neck and upper back if needed, too.
A lot can happen between and and October, when a new PM steps through door number 10. Cameron has said that he won't issue the official Article 50 notice, and will leave to his successor. That will probably cause the markets to tank again. The gun may be loaded, but someone still needs to pull the trigger.