It goes without saying, she was a controversial figure, during a controversial time. However, if you want to comment about her, then just do so respectfully; You can state you opinions be it positive, or negative and put it across in a way which you don't relate to name calling, or petty behviour - See
http://forums.overclockers.co.uk/showpost.php?p=24082154&postcount=238 for a perfect example.
BuffetSlayer doesn't like Thatcher, but puts his opinions across in such a way that it doesn't show distaste and that's the key thing. Moderators won't delete opinions which aren't crass, or distasteful, but will delete ones which relate to petty name calling, disrespect of a person and family who has just lost a loved one, or posts which break the boundaries of taste.
Keep it polite and on topic and there's no reason for moderation - even if you disagree with what she did for the country (or didn't do).