So I went for the 74/20 package in the end. A quick supplementary question. I assume I'll keep the existing copper phone line and that will provide our landline service, rather than some sort of voice over fibre service?
So a warning to anyone else. In the end, moving from 74/20 to 160/30 actually took about 3 months in total, due to real problems in how BT’s systems interact with Openreach.