Hi Tony-
1. drive to MIA; check MIA-FRA-LHR
2. fly to ATL on DL or Airtran for cheap; check ATL-FRA-LHR
3. fly to CLT; US is the hub so multiple routing options
4. fly to BWI on SW for cheap; take train to PHL where US is hub for multiple routing options OR take a rent a car to IAD where UA is a hub.
5. My experience with LH is that BD will have seats open up the week of the flight, especially in J from a leisure market like MCO.
Hope that helps!