@proseccoprincess - I’m actually going to disagree with what the others have said. If that agency is the best in its market, and you are located in Glasgow, it seems like a good idea. Just because an agency is your first agency, it does NOT necessarily mean they have to be your mother agency, especially in a market as small as Glasgow. It would be a different story if it were in a major market, or a network.
That being said- if you are seriously interested in modeling / traveling outside of Glasgow, I would suggest first approaching mother agencies who specialize in placement. I always advise this as a first step, as it really changes which doors will open for you in terms of agencies, but also because they are a very helpful resource in negotiating contracts / ensuring your general well-being.