Are there facilities to leave luggage either in Oslo or Copenhagen, i.e., a left luggage desk or lockers? Please provide as much info as possible. Thanks.
In Oslo, there are lots of lockers available at the train station: http://tinyurl.com/7kj8kec
The downtown train station in Copenhagen has left luggage downstairs. There is an attendant there to help you navigate the process of choosing a locker (as I recall you choose a locker, put your stuff in, then use a machine or talk to the attendent to lock it).