Look at KLM's discounted Business Class fares to various long haul destinations. Try Singapore for instance. Yes, you will have to fly via AMS, but that's why it's cheaper than direct flights from the UK. As for KLM's Business Class & service, it's not the BEST in the world but I find it more than adequate. If she's never experienced long haul Business Class before she'll be suitably impressed. There is better out there but it will cost more. If you book well in advance, I think that you will find some competitive Business fares. I don't work for KLM, just fly with them.
July 7/13: MAN-AMS-SIN-AMS-MAN £2740 p/p or via CDG (booked through KLM) £2206 p/p.
If you insist on 1st Class, have a look at Emirates. I believe they offer cheaper 1st Class fares than most.