I should have mentioned that there are separate forms when applying for a new service -- Pretty much as David has described for Scotland in that the PoCo requests a sketch of where the service is to be located and requests details of anticipated load (practically all new residential services are 100A single-phase, unless the load is very high).

Interesting about the integral isolator David referred to. I've yet to see anything like that south of the Border. The one I mentioned above was just a separate 100A DP isolator installed next to the meter by the PoCo (in this case it was East Midlands Electricity). Would you believe that they actually put a seal on the cover for the load-side terminals? Can't think why as their instructions then specifically stated to cut the seal and make your own connections.