The key is to press it for a few hours so it all sticks together.
The one over been doing for years- which I got off some cookery show- I think will be tastier than the one you linked to.....
Cut a lid off the bread and keep. Scoop out the bread from a white cottage loaf and line the inside with a layer of hummus. Layer the inside with watercress, chopped black olives, sundried tomatoes, mozzarella and repeat until full. Put the lid on, wrap in foil and put it in the fridge under some tins to set it.
I think it would be immense with lots of different ingredients so experiment!