You are so lucky a mother hedgehog is making her nest in your garden! One thing for sure is that you can’t interrupt her in any way. I would just be very careful that you don’t make too much noise going in and out of the shed. Maybe you could put some sort of padding, so that the door doesn’t bang too loudly. If it was me, I would be inclined to put a notice on the door reminding everyone to be quiet – so easy to forget, if you are in a hurry!
Make sure you stay away from the actual nest, don’t be tempted to have a peak – mother hogs can desert their young if disturbed, especially when they’re very tiny.
Good luck. Fingers crossed that you will see a little procession of hoglets in a few weeks time (3 – 4 weeks before the young ones venture out with Mum).