The 3m tower is perfect starting point for all your needs, whether it be inside or outside. Add extra parts later to reach higher or create long scaffolding runs ad roof edge protection.
All parts are compatible between towers, just add the narrow single platform width end frames to create narrow single platform width towers.
If you are looking for more versatility, then it might be a good idea to upgrade to the COREPLUS version because all the extras come standard, and are discounted.
The bolt on spigoit allows you to stack a narrow frame on top of the wide frame, which just allows you to have two different width 3m towers and still have the ability to stack them together as a 5m tower.
You can create a 4m or 5m tower by adding addition end frames, braces and platforms.