Don’t forget we ‘paid to be different’ on the F-35B not the A. If you want As...and it’s understandable that you do...you might want to factor in all those bespoke UK weapon integrations onto the cost. Plus whichever is cheaper...probe onto A or boom onto PFI airline-tanker thingy.
My bet would be on the next order being for more Bs...but I think the through life buy will be near as damn it 50:50.