Ireland already got the extension, to do same in England mps have to make an amendment to law as ireland did within a month. It is possible! it is a matter of mps saying yes to it. Petitions on change aren't taken to parliament. Gov petitions are.
If you want to extend validity of theory test, if you have signed the petition above on change.org please now go to https://petition.parliament.uk/petitions/307479 to sign for gov to do it!