The problem is that airlines don't know what to charge. Prior to COVID they knew how many people wanted to fly LHR - JFK return on a given day and how much they were prepared to pay, the algorithms in the booking system tweeked the fares depending on supply and demand. Now it's just a stab in the dark until things settle down and a basis to plan on is arrived at, assumptions are being made which may not happen regarding opening of borders and numbers of pax.
Personally, I would hold off until there was more certainty. If you're determined then only book on a major airline which is likely to survive and look at the refund policy, travel credits on a financially iffy airline which only operates on a single route that you'd want to fly wouldn't be much use. If I was in the UK, I'd be happier buying a BA ticket as they aren't as bad financially as some of the others, and if I got travel credits they'd be useable in future.
Note that hotel bookings for peak winter season destinations towards the end of the year are well up, it would be worth making a no deposit booking for accommodation as well if you buy an air ticket.