I don't suppose there is any way to expedite the license from the CAA? Having read a few other threads, it would appear that all you can do is phone in to check they're working on it, and maybe go and collect it rather than waiting for the post?
You can drop it off. They check all your paperwork is present and correct there and then and take the payment from you.
The return delivery is by courier anyway so I doubt picking it up (even if it was possible) is likely to save much time.