BA’s website is crap, but the app is surprisingly good for reward flights where you can look through the whole year at a glance.
SeatSpy is also brilliant for it, and I set up alerts and got return flights in business class to the Maldives several times. In that instance, I booked the premium economy reward seats so we could arrange the holiday, and then waited for club seats to pop up closer to the time. When they came up I got the email from SeatSpy within the hour and just had to phone the executive club hotline to pay the extra Avios and cash.