Oh dear, I see you are in Glasgow, which means some of the options available to us in the US are not as possible for you. Here are the two things I was going to suggest:
1. On the forum, there is a section called "Where am I? Where are you?" and under that section, are threads for different areas of the world. For example there is a thread for most of the US states, one for Australians and so on. I don't know if there is one for Brits but that would be the first place I would look. If you find that there is already one that British people are using, it is a great resource for finding people close to you who share the same interests. If there is such a thread, I would post on it, and hopefully someone closer to you can help you out.
2. In the use we have a resource called Craigslist which is an online classified section. You just find the city closest to where you live and browse through the various ads. Perhaps there is a similar thing in Scotland?
The other thing is, chickens don't necessarily need to be around others of the same age so even if you aren't able to find another 5-year-old, she will just be happy to have a companion of the same species. If you can find even a young pullet, that will be better than her being all alone. Good luck!
