Hi. I am a wedding photographer. What you mention here is totally doable.

If you are holding the wedding reception in a hotel, then you can do the tea session in the hotel ballroom. And the time taken for tea session and group photos usually last for about an hour. I have seen couples doing this but there is some additional charges for that, no pricey tho.

If you are holding the wedding reception in a normal restaurant, then straight ask them empty a VIP room for you to do so. They are usually helpful and restaurant usually don't charge, then you can always take the group photos later in the restaurant. You have your own backdrop right?