Why do you need to separate her? Is she in a nest where others will lay? A lot of people let their hens set in the coop with the rest of the flock. When the chicks hatch, they are pretty much immediately integrated into the flock while mama is still protective of them, and it goes quite well. The biggest problem I have is if a hen is in a popular nest, the others may come in to lay an egg and some of hers may get broken.
If you choose to let her set in the nest she wants, just put some bedding down, put eggs in, and let her back to where she wants to be. I just did that today. I have a broody that is in with general population, choosing to sit in a nest box that others may or may not use for laying. I am prepared to have eggs broken, but it may not happen. (She's my 3rd broody this year, so I'm not too concerned if she hatches many of her eggs or not - I already have 8 babies running around). Also, if you let her set where the others have access, be sure to mark the ones you want her to hatch so you can remove any "donations" laid by others. Check every day so you don't have development started, and get a nasty surprise when you go to cook your eggs for breakfast.
The reason I separated her is because there is one Chicken who it seems is out to get her and every time she comes out I plan to bring her back when she is I guess I could say out of the pecking order and when she Is very protective and aggressive I was hoping she would stand up to this hen I have no doubt she will with all those hormones. Another reason is when hatching the chicks may fall through the wire floor half the coop is wire floor and the other wood I have half wire to scrape the poo out