So to update anyone who reads this, my flight was this morning.
Qatar are in Zone A. Economy and Business and Ticket Desk.
It looked a complete mess in the economy line, but business/platinum line was empty.
The fast track's are closed so can't go through there. She made no mention of going to First Wing to clear security. I did see it is just BA First and American Flagship First. But as a QR Plat/OW Emerald maybe I could have gone.
Anyway went through normal security and then to the First lounge and got in no issue. Although at checkin she told me to use the Aspire lounge... which was strange.