Hi Martin, if you're shooting with a Nikon (which I think you are?) then I have a 300mm f/4 that you could borrow if you think that would do the job.
I'm going to be away for 2 weeks so won't be needing it. Depending where you are and if you want to stump up for shipping charges and a few Guinnesses
. Only deal would be if you break it you pay obviously
I'll need to know before Monday morning though.
Cheers, Martin