We’ve got a Vango Orchy 600 with the large canopy attachment.
We originally thought the tent would be big enough on it’s own; it’s just for the two of us. And it is big enough, but the tent soon feels small if it’s raining and you are stuck inside it.
With the canopy, we have moved the cooking gear under it and unless the rain is really driving in, we can keep the front of the tent open in bad weather, which is a lot more pleasant than having to shut all the doors and coop yourself up.
I’d go and try a few tents out if you get the chance at somewhere like Decathlon or Go Outdoors, noting down what they are for reference. This will give you an idea of what sort of size you might want, even if you don’t go for those specific ones. Try to imagine how much space a few chairs, table etc. will take up.
Our tent looked massive the first time we put it up, until we stuck a few bits and pieces inside.