Hi floriane
I’m pleased to hear you have hedgehogs there. It’s a bit difficult to answer your question very easily with the limited information we have, but I’ll do my best.
Hedgehogs do change nest sights, especially during the Summer, when males in particular may move fairly frequently. So, theoretically a hog may decide to sleep in your garden, depending on what it’s like, how much cover there is, etc. But equally, may not.
What type of dogs do you have an how well trained are they? Some of the terrier types may be more likely to attack hogs, but theoretically any dog could, but if well trained may be able to be trained to leave them alone. Are the dogs left in the garden on their own during the day?
Is it possible to make any access points other than your gate. If the garden is pretty much sealed everywhere else, the hogs would only be able to enter/exit via the gate. Again, how big is your garden, what sort of boundaries, etc? But ideally as many entrance/exit places as possible would be good. If you have fences you could either dig some hog sized tunnels underneath or make cd sized holes in the fence.
In general the more habitat the hogs have the better, so it would probably be nice for them to have access to a bit more. Maybe you could provide some hog boxes they could rest in during the day, provide more cover, if there isn’t plenty already, make lots of entrance/exit holes, etc. and train your dogs to leave them alone or at least keep an eye on them.