I know you've already decided on Exeter and planned for it, so I shouldn't really put you off, but it is a British regional airport which is not exactly GA-friendly: exorbitant landing fees, high vis vests, security gates, interminable treks to pay landing fees through a little window, big apron etc. etc. For somewhere much more GA friendly, but still with a decent-sized tarmac runway and in the middle of beautiful countryside try Dunkeswell. A much more pleasant experience.
David