There are no opportunities with BA for regional commands really. It's Heathrow or Gatwick only. Possibilities with GSS in Standstead as well as openskies.
Also, I would say 15 years to a shorthaul command is VERY pessimistic!! Up until the recession hit, it was 7 - 8 years. What it will be in two years times nobody knows. That depends on retirement/expansion etc... Certainly won't be as long as 15 years though!!