Thanks NoraB, your reply is very helpful.
To answer your intrigue, the gp said she could refer me for the tests directly but she thinks it would be best to speak to a specialist first (I don’t know if I said but all of this, including the gp appointment, is through my work private healthcare). Part of me assumes her reasoning for doing this is because it is all through the private healthcare and they do tend to refer you into a specialist (with money not being a factor as it’s all covered by insurance) , and then the irrational side of me thinks she’s passing it on to someone else so that it’s not her who gets sent the scan results and has to give me the bad news…

She thinks I had a focal seizure. Which matches what I had thought (from my Googling, after I’d had it). I’ve resisted Googling since, as I know it won’t end well. As you said though the seed is already planted from when I did Google (focal seizures being the most common symptom of brain tumour, etc.) and my mind has totally latched onto that. I’m lucky to have a very supportive husband who is good at keeping calm, and who correctly reminded me yesterday that a referral to a neurologist is actually the outcome I wanted, so in that respect the process is going the right way.
You’re totally right- how I deal with this is in my hands now and I’ve got to get a grip of it and try to stay calm.