Any MoD tech library or OC Pubs on a UAS should be able to get a set for you without difficulty. They aren't classified.
More usefully if you are doing some real test flying on the type, ring up the "Information Centre" at Boscombe and see if they'll release you copies of the original FT reports - they'll tell you far more than the POH will.
I've done a bit of flight testing (and a few more hours just enjoying myself) in the delightful bloodknot in the past, although I don't have a set of pilots notes. If I can give you any pointers on the type, drop me a note.
G