No special access issues
There are many ways to access kotiluoto.
You can get there with a boat. Land to the north side of the island. There is a metal thing you can tie your boat to. If you are member of Helsingin navigointioseura you can also leave the boat to the dock.
If you do not have your own boat the island can accessed by getting a ticket to FRS's itäinen saaristo reitti. They will go to multiple islands including kotiluoto.
They island is also not far away from Jollas meaning that you can get there by doing little bit of swimming. This is a nice way to get your muscles warm for the hard boulders.