Thanks for the suggestions ladies, apologies that I haven't been back before now!
I think UttaRetch and Catllar are right, it's a peach skin. Would you know that my local fabric store actually have silk blend peach skin in at the moment? I got quite excited as they had a pinkish colour in there, but sadly when I took in the top I'm trying to match, it's much too pink. I realised that I don't need to match the actual colour, it only needs to tone with the existing pieces in my wardrobe, so that might make it a bit easier to find the right fabric. I'm also not fussed on the actual type of fabric - eg any drapey suiting type fabric will do.
Thanks for those links surestitch, I've ordered a sample of each of those, we'll see what they look like! They also had a peachskin so I've grabbed a sample of that too!