I think you fully understand to choose what type of hosting
plan to host Sitefinity CMS. But there are still some shared hosting plan out
there which allowed new website and isapi filters.
You mentioned that you
need to host a school website. How much are your target audience that you
expected? If your need your Sitefinity site to handle a lot of simultaneous
connection, it is advisable to choose dedicated asp hosting plan.
starting, maybe you can host it on a shared hosting plan. You can consult the
support team from SeekDotNet.com for the Sitefinity hosting