Louhy go to settings in the main menu (Settings not Budgie Settings).
In settings go to Keyboard. Scroll the end of a long list of keyboard shortcuts you can there add your own custom keys.
For Terminal you can add a shortcut and put gnome-terminal
in for the command and then choose your preferred shortcut key, Ctrl+Alt+T, or indeed whatever you like.
If you can't find it come back and I'll post a few screen shots 🙂