Be careful with British Gas, I had solar panels fitted, BG told me they will not accept the reading from the meter fitted by the solar panel installers, which was fair enough, I would need a smart meter fitting, again no problem, then when I completed the forms to get paid for export, they said they were the wrong format, I must have completed the forms at least 5 times, each time had to wait before rejected and no one seemed to be able to tell me what I had done wrong, I had signed to have a tariff for one year, with a £75 fee if I changed before the year, so waited until it ran out, then moved to Octopus, only to find out, nothing to do with how I had filled in the forms, I needed a second MPAN number, all sorted within two weeks, and at last after 18 months got paid for export.
It seems BG staff have not got a clue what they are doing. You may be lucky, but you can also end up going pillar to post trying to get things done. We have basic three different sets of people required to do the work you want, the DNO moves the head, the billing agent (BG) move the meter, and the electrician provides the isolator for the meter to be connected to, and getting it all done without being without power for an extended time, and/or costing a fortune, is hard.
I know Octopus do have their own electricians, as I know they can install EV charging points, and BG may also have their own electricians, they also have their own sets of rules, so just because Joe Bloggs down the road can fit something where you want it and how you want it, does not mean BG will do the same. And the same applies to Octopus, their electricians have to follow company rules, as well as the national rules and regulations.
Also, my son was doing a major rewire of his house, and it was agreed that the DNO head would be moved, which did happen, but it took three years. It seems his supply was shared, but it was not on the records it was shared, and clearly no way-leave, as it would seem 50 or more years ago some electrician had taken it upon him self to dig one trench instead of two. He had a quote, and it was honoured, but the building work both he and next door were doing was held up for three years as a result.
It looks an easy job, and it should be, however be careful as it can work out very expensive.