Caterpillar advice

[Dlsmith]

Hello,

I found a caterpillar on my curtains on Saturday. I'm assuming it hatched off of flowers I had over Christmas. I'm not sure what kind it is and because I'm on my phone I can't upload a pic to the Gallery. I have searched pictures but still unable to identify it.
I put it in a tub with lettuce leaves (the only leaf I could find at short notice) luckily he just started eating it and has been stuffing his face since.
Today when I came home he had crawled away from the food and was lying very still, I assumed the worst but decided to move him to a large vase with 3 inches of soil and some sticks stuck in. He straight away climbed the sticks for ages, like it was a little jungle gym. I assumed he was going to stay there and cocoon. Next thing I couldn't see him and could just see a bum sticking out the soil. I then assumed he's a moth but before bed he was climbing the sticks again! He hasn't eaten most the day but I'm unsure whether he's getting ready to pupate. Any help would be appreciated.

[Dlsmith]

also can anyone help identify him