Hello!
Welcome to FT and the BA Board!
Well, you have sort of answered your own question! You are correct that the CE product on the LCY route still has the same seating as Traveller. No additional width in the seating, and no empty or compressed middle seat in the row.
Obviously the meal and stuff will be CE, but if the space is more important, then go with the LHR flight as it will have the empty seat in between.
Regards,