Thanks!
I started calculating the taxes just after I posted my first post. I come to EUR1235,-. Slightly more than I expected, but not too bad. I knew using LHR would cost extra, but what can you do?
Going A class to DXB for EUR300 is not too bad. (Too bad they view the tickets as seperate even if I will only transit through LHR...

).
Good advice on leaving scarce flights open. SCL - IPC is the only one that is really scarce, but I will try and finalize my dates through to CUN.
Can you also upgrade ONE from economy to D?