Anytime You Get An Error Like You Describe...
..particularly as it relates to downloading apps, upgrading apps, or apps bombing out...close out all apps in your memory (double click home button; press any app until x appears, and close each one) then press your sleep button and home button together until you get the slider to turn off your iPad.
Wait a couple of heartbeats, press the sleep button until you get the white apple logo, sign on and you should be good to go. This is equivalent to the ctrl+alt+del in the pc world.
Hope this helps.
Another bit of advice, I often turn off my iPad at least once a week. The rest of the time it is being used or in sleep mode.
BTW, welcome to the forum Clumberdog