Nick,, i think you are going over the top planning, it is easy as chips over there,,,too easy to convince yourself every where will be hidden or closed,,WRONG,
Northern Europe is made for touring,,every where is a visitor destination,they are all geared up for you to call by, all you need is a waterproof pastic map and a tank full,,it really is easy,
There are loads of hostels,Formula one and others,only 30 euro a night,,i know you want to camp ,,there are camp sites everywhere too.