E.g. www.bbc.co.uk/news would be:
category = news
description = news and magazines
content rating of G.
The content rating will give you a good idea of if a site will be available for your school, anything G or PG may be allowed, anything else will be blocked. You can use this in conjunction with the description, we have most of the following areas available within schools:
The above is a representation of most schools configuration, some schools have requested specific types of websites to be blocked/unblocked so there is still a chance it may/may not be accessible within your school, if blocked you would need to get it requested by one of your schools authorised users.