Mapping foreign characters on a Windows keyboard

I recently moved to Denmark from the UK. My laptop is therefore also from the UK and I've hit a slight problem. In the Danish alphabet, there are 3 extra letters, å,æ and ø.

While I can set up a keyboard shortcut to use them in Office (through symbols) I can find anyway to do the same throughout the whole OS.

Does anyone know how I can do this ? It's pretty vital.

On a Mac, it's as simple as just long pressing the correponding 'English' key where it then gives you the relevant foreign keys to that letter, just like on iOS/Android/WP. Hopefully there's a way as easy as this on Windows.