Hi
Whether paying an extra £1000 pp is quite subjective. Realistically, the diff between J and F is much smaller than that of W and J. There are many threads that compare the two experiences. I’ll list a few key differences here such a wider bed, fancier Champagne, and PJs.
If you’ve never tried BA F before, I think it is a reasonable rate to experience it for once. If you’ve flown F on other airlines (especially the likes of EK), you might be disappointed.