Nope. Not that I know of anyway. I have one sat in my account so if you let me know what route and dates you're interested in I can look quickly, though if you were wanting to just browse I can't really help with that.

One thing you'll find is that there isn't much extra availability from London, especially on popular routes, but the real goldmine is if you're willing to start from other UK airports like MAN, EDI, NCL etc. Whereas regular reward availability is done on a sector by sector basis (so to get a MAN-LHR-HND redemption you need reward availability on both flights), the extra availability is based on fare class, which is based on the overall routing, so since MAN-HND is much less popular than LHR-HND, there are loads of extra seats from MAN.