Excellent suggestions so far by others....^

I will add another choice (though this may be more expensive according to your research)....LH via MIA

This would be direct and avoid connections in London or the US....I believe the A380 flies FRA-MIA (if this is interesting to you)....the drive time would be similar vs TPA to southwest Florida (although you do not mention if FT myers is your exact final destination)....the negatives seem to be price (I did not check fare price differences), and dealing with MIA/transport out of MIA....

It sounds like you are trying to balance all things to find the best all around deal....the FT way....^

Good luck