There's a book, "Little Nellie 007" (ISBN 978-0-907595-75-5) by Bruce Halpenny. It'd probably have most of the info you're looking for. I've read a little bit about Little Nellie, a Wallis WA-116 Agile. It's said that there were surprisingly few pics taken of her during the mods needed for the Bond movie You Only Live Twice...and that most pics you can find of her are more recent, as she's a bit of a celebrity.
Try looking for references for the WA-116 instead of Little Nellie...you'd probably get more hits for the WA-116 than for Little Nellie.
I've got one - it's kinda typical old school Airfix...a little clunky, with less than "Tamigawa" fit and detail. To make a good model, you'll need to refine and detail many things, such as the frame, the mast, the spartan cockpit, the rotor head (I don't know if that's exactly what it's called), the engine...and the decals are hard to fit. I ended up masking the circles around the nose.
I'd suggest buying the DVD...and then you can pause the movie anywhere you like...maybe take screen grabs so you can use that as a reference.