Most Mosques are open to non-Muslims provided one is modestly dressed and has come with the curiousity to know about Islam. If you attended a Mosque during friday prayers you may have the opportunity to listen to the sermon (and witness the prayers) which I would assume will be in English in addition to Arabic or any other language. It is best to first confirm with either the Imam (priest) or a Muslim you know before you attend the prayers to make sure it is in a language you understand.
If you are intersted in Islam please try to read up about the basics of Islam and try and gain an understanding of Islam. Sometimes one may come across Muslims/behaviours that may turn you away from Islam. But when you have a good understanding of Islam you will not be deterred by anyone's attitude. Here are some links to gain an understanding of Islam.
http://www.islam-guide.com/ - http://www.islam-guide.com/
http://www.islamicity.com/education/understandingislamandmuslims/ - http://www.islamicity.com/education/understandingislamandmus lims/
Please feel free to ask any questions you may have on Islam.