Slight twist to the original post - If you were an experienced airline pilot with 4500+ hrs flying the line, but through no fault of your own suddenly find yourself jobless would you shell out the £6000 or so to do an FI course?
It's something to do, its something you would enjoy and as has already been stated its a way to "keep your hand in". I imagine for some schools the fact that you've flown for airlines already would be a bonus when considering employment, conversely of course there may be others that would prefer a "self-improver".
With regard to the original poster, my personal opinion says don't bother save your money too. It's a hellish situation. We're not talking about a few job losses here, we're talking thousands of full ATPL experienced pilots now looking for work. A lot of them have seen this before, the airline industry is notoriously boom and bust. Have you tried Ryanair? They are after low hours guys, but it will no doubt cost you more than £6000. At least you may get a salary at the end of it.
Please respect that I'm not trying to shatter yours or anyone else's dream and by all means try anything you can to get your first job. Just realise that it is a gamble and you should only ever gamble with what you can afford to loose.