Film based on popular E4 comedy expected to sell more than 1m DVD copies in week of release The big-screen spin-off of The Inbetweeners is on course to become one of the biggest-selling comedy DVDs of all time after shifting nearly 600,000 copies on its first day on sale. The Inbetweeners Movie , which was released on DVD on Monday, is expected to top 1m sales by the end of this week. It would …