The cheapest domestic Alsie Express flight is flying Kastrup Copenhagen to Sonderborg, which is £186. This round-trip flight has 0 stops. For a one-way domestic Alsie Express flight, the cheapest route is Sonderborg to Kastrup Copenhagen (0 stops) for £95.
No, there are no Alsie Express flights from London Heathrow. However, Alsie Express does fly from Sonderborg on a weekly basis. You could also fly with FlexFlight from London Heathrow as an alternative travel solution.