Ok, update on this, sorry it's been such a long time.
I've actually got quite a bit more done, and then I realised the fabric isn't big enough.

There's not enough space at the bottom so I won't be able to frame it properly, especially with it being linen and all.
Also, somewhere along the way I messed up, so a section on the bottom right is a good few squares up from where it's supposed to be. I could probably sort it out but it would annoy me too much.
So, am going to give it up and start it again.

Am a little p'eed off as I'd done quite a lot of work, but it's got to be right. Won't start it again straight away (have to replace some of the threads I've used anyway), but hopefully pretty soon. Think I'm also going to go for blue fabric, as the sky and part of the stream is left unstitched.