Hello Gill.
I made Tiggy Towers out of a redundant wooden bread box. The important points are
It must be weatherproof, I used floor insulation plastic sheeting, three layers.
It must be sited somewhere sheltered from wind and rain, mine is under some bushes in the back garden, it's out of the wind and safe from predators. It must also be sheltered from winter weather. The cold is one of the biggest causes of hedgehog fatalities.
You could put some hay or dry leaves in if you wish. tiggy turfed it all out and put his own in. Fussy wee git! :o}
Hedgehogs live for about four to six years in the wild. They can live a bit longer in a safe and secure environment. Tiggy is six now, (that's about eighty in human years) but he's fit and healthy and enjoying himself.
I hope this is of some help to you Gill.