Found this morning on ebookers and Expedia through Kayak some flights from London Gatwick via Dublin to MCO in April, May and June flying with Aer Lingus starting from £377.
April flights from £377
http://www.kayak.co.uk/#/flights/LON-MCO/2013-04-13/2013-04-27
April flights from £377
http://www.kayak.co.uk/#/flights/LON-MCO/2013-04-06/2013-04-20
May flights from £398.
http://www.kayak.co.uk/#/flights/LON-MCO/2013-05-11/2013-05-25
June flights - £405 from Southend Airport, £409 from LGW and £419 from LHR
http://www.kayak.co.uk/#/flights/LON-MCO/2013-06-08/2013-06-22
April flights from £377
http://www.kayak.co.uk/#/flights/LON-MCO/2013-04-13/2013-04-27
April flights from £377
http://www.kayak.co.uk/#/flights/LON-MCO/2013-04-06/2013-04-20
May flights from £398.
http://www.kayak.co.uk/#/flights/LON-MCO/2013-05-11/2013-05-25
June flights - £405 from Southend Airport, £409 from LGW and £419 from LHR
http://www.kayak.co.uk/#/flights/LON-MCO/2013-06-08/2013-06-22