If a civil ceremony, the bar opens at midday. If a church wedding, the bar opens on guests arrival from church. It remains open until last orders at 11.30pm, so you can get a drink at any point.
This is an exclusive bar only available to the wedding party during an event. This does mean if you are staying over for 2 nights in the accommodation you will not be able to access the bar except for during the wedding you are attending.