CaledonianGirl,
The only thing you can do is put your name on the "my opportunities" transfer list when it opens up again in October.
Unfortunately there has been virtually no transfers actioned to GLA for quite a few years now and I really wouldnt put my hopes on transferring there within the next couple of years.
If I were you and the commuting was getting too much, I would either move closer to LHR or find a job in a Scotland.
As always things are liable to change but IMHO there is virtually a 0% chance of anyone transferring to GLA.
I hope it works out for you whatever you decide.