In the House of Commons MPs are able to present a Bill under Standing Order No 57 on any day on which the House sits. A Dummy Bill consisting of the short and long titles of the Bill and the names of any supporters can be presented by a backbench MP in order to introduce a Private Members' Bill.
Further information on this subject can be found from the following links.
About Parliament: Bills
Bills before Parliament
Related glossary term: Private Members' Bills