Im just going to bullet point, however make sure that the start reads match whats on the exchange tag. If they have done an exchange it may of been because the meter was too old.
standard victorian end of terrace, three bed house = Very large house to heat x6-8 radiators, no heating from another neighbour with it been an end one.
heating on for 5 hours a day, really you dont need it on for this length, try it for 2-3 hours spread throughout the day. Make sure also that the thermistat is set to say 15.
It would be worth you speaking to energy efficency.