Q.Is My Pot Suitable For My Fig?
i have 1-2 inch layer of stones at the bottom to let the water drain through the soil. But I’m starting to wonder if I should have some kind of removable tray at the bottom?
It’s been growing well, although now has started dropping a lot of leaves everyday. I have raised it off the floor as I have underfloor heating and thought that probably wasn’t helping.
I have attached a photo. If you have any advice I would love to hear from you. I am just going to continue to monitor it at the moment now its raised from the floor.

Certified GKH Gardening Expert
There are several possible reasons for the problem. This article should help you determine what the plant's responding to:
https://www.gardeningknowhow.com/houseplants/ficus/ficus-losing-leaves.htm
Also, current research says the rocks in the bottom of the pot don't prevent root rot. It's really best to have several holes in the bottom of the pot for drainage.