Britain isn't broke, we just don't care about defence. US economy is in a worse position relative to where it was, yet it retains defence spending >2x higher than Britain per capita. Britain would rather keep welfare spending high, which is fair enough from the politicians' vote-buying perspective.
...and this is why the western world is in the trouble its in right now. You want to spend more money on less because the F-35 has a much cooler cigarette lighter. There's a term called "economy of force". Inflict the maximum amount of damage on your opponent using the minimum amount of force. The Rafale can truck bombs just as well as the F-35 and can do it cheaper. Also since you have more of them compared to the F-35 you can attack more targets simultaneously.
Or rather, much cooler everything. If the criteria was just to haul bombs around at the lowest price per mass we would use freight planes (converted airliners, or converted business jets for carriers). Ability to survive, and to detect targets, is unfortunately necessary also, and that's what causes the expense.