I doubt QR will cancel any of those flights, and there is no BA (because its a BA ticket) free change of destination or refund for border restrictions.* In this situation it would have been a lot better to book it as a straight QR ticket for their no-quibbles no reason required full refund. Hopefully Test N Go is reinstated.
*If it was booked as a BA Holiday you'd possibly have more legs to stand on refund wise