Which document guarantees right to fair trial, right to petition government and free speech in parliament?

The English Bill of Rights is the document that guarantees the right to a fair trial, petition the government, and freedom of speech in the parliament.

In Britain, 1689, the Bill of Rights was one of the fundamental instruments of the constitutional law. It registered in statutory from the struggle between the Stuart kings and the English Parliament in the 17th century. Its principles were accepted by Mary II and William II in the Declaration of Rights. 

Well actually there are several including the deceleration of independents

False, you should consider everything before making a final decision so you know you are making a good choice.