A practical free starting point is Hugin for stitching your photos into panoramic images. If you want a navigable virtual tour, the usual workflow is:

1. Shoot overlapping images for each location.
2. Stitch each location into a panorama with Hugin.
3. Convert the panoramas into cube image maps if required by your tour software/viewer.
4. Add navigation links/hotspots between locations.
5. Export in a web-compatible viewer/output format for embedding on the school website.

Key precautions:

• Plan each camera position so visitors can move logically through the building.
• Shoot with enough overlap for reliable stitching.
• Keep exposure and camera position consistent within each panorama.
• Check that the final tour format works with the school’s website before committing.

So: use Hugin for the panorama creation, then choose a virtual-tour tool/viewer that supports hotspots, cube maps, and website embedding.