I called 0800 727 800. When they cancelled my trip they rebooked me for the following day and returning a day later too but I had flight connections and hotels booked, so I told them it was unacceptable. I don't really know why they rebooked me, as the flight was to Malaysia, which is closed to visitors anyway. My companion voucher has been extended from the end of January 2021 to July 2021, so six months.
Thanks again, that is really helpful. It gives me a bit more reassurance about my trip. I'm now keeping fingers crossed that we don't get caught by the Government saying no travel and BA saying that the flight is going anyway!!