Jet2 is a holiday airline, they are not at Stansted to compete on seat only sales. They are in the South East to sell the whole holiday package.
Destinations will be typical Med ie: Palma Alicante, Malaga, Ibiza Canaries. Faro, Cyprus and Greece.
Mention was made of regular New York flights for Jet2. This will not happen, the 757's are far to busy in the Summer to be waisted going to New York and back.
The new 737's will be turning up at more than one a month so leasing in will not be necessary specifically for Stansted though they may well lease in airframes in the peak season as they have done for many years.