ickle black box - here's my opinion.
I think you would be better off saving your money rather than doing an IMC rating. The JAR IR course doesn't acknowledge the IMC rating, so it's designed for people only with PPL or CPL ability. Subsequently, even with very little instrument flying experience, you shouldn't struggle to get through the course. £1500 could buy you 5 or 6 hours extra training (nearly 15 in the sim), which would be more useful to you.
If/when you are hour building though, it would be advisable to practice things like instrument flying, rather than just fly around aimlessly.
I don't think you will get an Approved IR course (55 hours) for under £10,000 in this country - and then add
£1000 for the test. On the American side, IFTA and Pan Am Flight Academy are approved to do IR's but I don't know how much they charge.
Before you can start the course you need 50 hours PIC cross-country, of which 10 must be in aeroplanes.
Hope that helps.