No-one will care much about what your hair looks like so try not to worry. You’ll need to visit the salon anyway at least 24 hours in advance for a skin test, so grab a scarf or a sun hat and trek into town.
Any salon that doesn’t insist on you having one, suggests to me that they’re happy to take short cuts and therefore, are probably not great at colour correction.
Before I went into hairdressing, I did a home bleach that left me with very bright ginger hair and I was having a job interview later that day. I decided that no-one at the company had met me before so they wouldn’t know that my awful hair wasn’t meant to look like that.
I brazened it out and got the job, then got my hair sorted afterwards.