Hi guys
Thanks for all the feedback and encouragement

I've rendered the last 2 seconds worth and re-comped the animation to include a depth pass, some grading and de-noise. It also now has an audio track. Its uploading now to Vimeo but apparently will take a couple of hours!! I will try Martins (dandelO) displacement trick on a short section, see how it pans out. I've seen plenty of very still forests with little of no movement in the leaves so if used I think in this case it would need to be very subtle. The other option I may try for another animation would be to have some birds or butterflies flying about breaking up the light shafts.
I'll let you know when it uploads but it may not be tonight! Socialisation calls!
Cheers
Richard
Ok it's uploaded but will take a little more time for vimeo to process, probably ready about 7pm UK time at which time I'll be out!
New version is
here and I have added the link to the first post