How much time am I entitled to take off when I get married?
Congratulations on your good news. However, I was slightly confused by your question. Teachers are bound by a fairly rigid form of flexitime that divides the year into terms and "holidays", or non-teaching times. So you are expected to arrange discretionary activities, such as getting married, not in term-time.
It is recognised that non-teachers don't play by the same rules and you can usually get a day off for a wedding of a close family member, but not your own nuptials. There are entitlements for moving house and for certain other events.
I believe that as schools start to remain open longer each day, and for more weeks of the year, the historic contract under which teachers have been employed will eventually be replaced by something more akin to that of other employees. At that point, it may even become possible to arrange holidays during term-time without taking unpaid leave.