All the best to you for your appointment next week.
I don't live in your country, so can't even begin to make suggestions really. I just wanted to wish you well in finding someone who can help you.

The only other thing I can suggest (and you've probably done this by now) would be to contact NINDS. They might be able to offer suggestions for a referral in your area. I thought Yale would have someone, but I couldn't find anyone on their site specific to arachnoid cysts.

NINDS - arachnoid cysts

all the best to you.