If the work has to be done, all you can really do is check very carefully beforehand or as you go along and if you find signs of a nest leave the area around it until you are sure that the hedgehogs have moved out. You shouldn’t disturb the actual nest to see what’s inside because a Mother hedgehog might desert or kill her offspring if they are still very young and she is disturbed. If you think a Mother hedgehog has deserted her young or if you see very tiny hedgehogs nearby on their own, you will need to take advice from a hedgehog rehabilitator. You can get the number of your nearest one by ringing BHPS on 01584 890801.
You might like to speak to a rehabilitator in advance – they may be able to give you more comprehensive guidance. Better to to be safe than sorry.