According to the map, here, Rome and Ancona are about equidistant from Pescara:
http://goitaly.about.com/gi/dynamic/offsite.ht m?zi=1/XJ&sdn=goitaly&zu=http%3A%2F%2Fwww.init aly.com%2Ftravel%2Finfo%2Fairport.htm
However, the Appenine mountain range lies between Rome and Pescara, which means that both road and rail travel would take ages.
So, your best option would seem to be to fly to Ancona. Ryanair flight FR124 departs from Stansted at 0955 daily. (Landing at 1310). The return flight, FR125, departs from Ancona at 1335 daily. (Landing at 1555).
Castelferretti railway station is in front of the terminal at Ancona Falconara airport. The train journey into Ancona takes about a quarter of an hour. From there, you can take a direct train to Pescara. If you caught the 1400 service from Castelferretti, you would arrive at Ancona at 1417. The connection leaves at 1444, arriving at Pescara Centrale at 1603. (Those are current weekday times).
Train times are here:
http://www.trenitalia.it/en/index.html
Chris