Taurine tablets are available from Holland and Barrett shops in the UK. I think they cost about £7 for 30. In the Body Builder section of the shop if I remember from last year. I started taking them and then chucked the remainder after a painful side effect. Maybe it was not mixing too well with the rest of my meds. Anyway, stopped them and the side pain receded.
It's great that there are so many expert business advisors on this thread, particularly the ones who almost ran a whelk stall in their previous existence.
One thing that is not forgotten is the passport, so buy some large sticky labels to write a reminder message and stick one on the passport in the days before travel. To avoid forgetting that you might put reminders on your Google Calendar immediately after making the flight booking. Good luck.
There used to be a cheaper and simpler alternative online Scottish form which was acceptable for O/A applications. Others might know if still operational.
The guy who tries it on in the queue always sent back. For Fast Track must show evidence of BC ticket, or fall into one of the exemption categories. In the past, airlines would hand out a Fast Track coupon to BC passengers.