When you have no control over what is being served at a large catered affair like a wedding, an annual awards dinner or charity event, you must approach the event with low expectations and know that ingredient disclosure will probably not be as readily available as it can be in restaurants. Catered meals are ordered well in advance, are often prepared off-site, and brought to the venue in warming ovens. The chef or catering company owner may not be at the event to ask questions about ingredients, and the servers may not know. You might be at the mercy of your educated guess-work.
Before you sit down for a preplated meal, try to ask a server as soon as you can what is being served. This way you can get an idea if the main course will have gluten and if so, you can try to request basic adjustments before your plate is served. Given enough lead time, the catering staff may be able to put something special together for you. But in any case, try to avoid waiting to see what is delivered to your table. Instead, be proactive in the beginning. Special requests made after the meal is served can lead to numerous delays with your meal, or worse, you could go hungry.
If you know the host or organizer of the event, try to arrange a special meal days in advance. With buffets, gluten-free options are usually limited and you’ll have to do your best to choose the items you believe will be safe. Bottom line: Eating ahead before you attend a catered affair is always a good rule if you don’t want to take any chances.