Thank you again . By way of an update, the consultant was not particularly helpful. I asked if she would be OK to travel and if he'd sign the Fit to Fly form and he said it was up to us, but to bear in mind he would be making an appointment for her back in clinic, she needed an MRI and adding it was not his job to sign the form and that was a job for our gp. But if we did decided to go she should take an aspirin before the flight and raise the alarm if she got any pain in her calf. There is still swelling in the knee but another 48 hours before we go so hopefully will reduce a bit more.

So GP duly contacted and kindly signed form (without seeing her) just asking if she could bend her knee and sit in a normal seat. Happily on that front the consultant said the splint had to be removed and she could / should bend the knee - so that's a big help/relief.

Also managed to nab a cancellation for MRI last night so that's all done too! (Always pays to go to the department yourself and ask!)

And - I have also booked seat 6a so fingers crossed the curtain doesn't move!

So we have certification, no longer need 3 seats, have assistance if we need it and generally good to go - but I am now a bit anxious re dvt risk having read some of these messages so feel I shall need to do a little more research before I make final decision.

Thanks again for all the good advice - very helpful. I certainly wouldn't have thought about the form so hopefully this thread might be useful for others too.