Not sure what you mean by "aerial work" exactly. For off-airport landings, you need another permit, which has the following restrictions for non-commercial flights:
- no landings at night or on sundays
- no landings above 1.100m
- swiss-registered helicopters only
As I said before, none of these restrictions apply for landing at the designated mountain landing sites if you have a current mountain license. You can legally land there on sunday night with a UK-registered chopper.