SchoolGuardian has a firewall built in - it was originally devised as an "all in one" package for schools - though many schools are now finding they don't need a firewall (got one, perhaps even LA/RBC provided) so are going for NetworkGuardian instead, or that they want a firewall, but need a hardware solution, and so go for one of the UTMs.
Hope that helps!
Cheers. That helps alot actually, its nice to have the option.
If you decide you have gone for the wrong one, it is generally easy to play swapsies :)