Just call the dvla, they wont give you info, but you can give it to them and they will confirm, ie is the car registered in my name/address yet?

If not, download the v62 iirc and send it off to apply for it.

You could always call the seller and ask if they have sent it away as they can be fined for not informing the dvla and so if you politely enquire with them on the pretence you didn't want to drop them in it, they may suddenly remember they had forgot and get it sent off.