I see that there is a supplementary page for web programers to add more T&C, need an option for NON programers / HTML people ! 
We used HTML as it’s flexible and can be used to create a high level of customisation. Also it’s one of those areas that you typically only need to setup once.
You don’t need to use any complicated HTML for a basic set of terms and conditions. If you’re struggling try a conversion tool.
Would it be worth dropping in a wysiwyg editor option like http://jqueryte.com for those who are less confident at HTML? It shouldn’t change anything much (if at all) on your side, it just turns a regular textarea into a rich editor on the client side.
I find these WYSIWYG editors can generate extremely verbose markup. There’s also the risk that it may apply styles that the PDF generator doesn’t like and we’d have a hard time getting the output in the editor to match the PDF rendering.
I think a markdown editor is the way to go, similar to what’s being used in the forum message composer. It’s simple to understand, flexible and should cover most formatting requirements for text based documents.