We started camping last year and got rained out in Swanage. It was pretty miserable tbh, everything was damp and DH spent ages pegging everything out so it was secure. He still moans about how it didn't feel like a holiday/ no time to sit down and relax/ took too long to put the tent up.
DC loved it and don't remember the rain. I'd really like to try camping again, especially as DH is a teacher so we have a nice summer holiday to fill. What reasons can you give why we should buy a FC and how it will be better than camping in a tent? Hopefully there'll be some. 
Thanks.