Given that it's the revenue from the phone calls and texts that pay for the prize, it's unsurprising that that the 'loss leader' way of entering by email has now been dropped. The cheapest way to enter now is actually by post (but they hide that information away!)
"Post – send your entry on a postcard or on or within an envelope to TMG 37, PO Box 7558, Derby, DE1 0NQ. Entries received on anything other than a postcard or envelope will not be accepted"
http://www.itv.com/termsconditions/competitionsandvotes/?oid=1199&type=tcs&origin_type=tcs&origin_oid=all