Regardless of where you raise chicks they need food, water, protection from predators, and protection from the environment. Protection from the environment means adequate ventilation, protection from breezes, and a spot warm enough in the coolest weather and cool enough in the warmest weather.
In colder temperatures ventilation is about removing excess moisture from the air to prevent frostbite. Danger from a cold breeze hitting them should be self-explanatory, not good. This generally means openings above them so moist air can escape but solid walls down where they are to stop direct breezes. Moisture comes from their breathing, their poop, and open water.
Chicks need warmth until they feather out, usually around 5 weeks of age. So they need a heat source. A lot of people use heat plates. I don't know where you would get one in Scotland, maybe online or at a feed store. Some make a shelter out of a heating pad. You might do a search on this forum for information on both of those. Other people use various types of heaters.
I use a heat lamp. Although they have been used for over 100 years many people on this forum are scared silly of them. To me, any heat source is a fire or electrocution risk if you don't use it correctly, including heat plates and heating pads. I do not use the clamp that come with it but firmly fix it in place with wire or chain. I do not use fiber or plastic cord that could melt of burn.
The big problem brooding out of doors that is different from indoors is the temperature swings. I use a fairly large brooder and heat one spot warm enough in the lowest temperatures. When the weather warms up that area can get too hot, hot enough to kill them. So they need a cooler spot to go to when the weather warms up. Straight out of the incubator my chicks are really good at moving to a comfortable place as long as they have options. On really cold mornings the far reaches of the brooder may have frost on it but the warm spot is toasty warm. On hot days the chicks may be at the far edge of the brooder away from the heat. What I see a lot is that they like to play in the cooler areas of the brooder until they get a bit chill, then go to the warmer area to warm up. I keep their water close enough to the heated end that it does not freeze.
To me that's the main thing about brooding outside, make sure they can handle the temperature swings.
Good luck!
