Not sure if it would be any helpful adding info to the sector guide, but if anyone's reading this, generally on 3 sector sites, the networks will follow some sort of pattern similar to this (varies by site etc):
Vodafone/O2 in Vodafone host: 1x (East, around 120°), 2x (South, around 240°), 3x (North, around 0°)
Vodafone/O2 in O2 host: 1x (North, around 0°), 2x (East, around 120°), 3x (South, around 240°) (might be a bit wrong here since I'm not in an O2 host zone regularly and taking a glance at O2 maps doesn't really help me here)
EE/3: 0 (North, around 0°), 1 (East, around 120°), 2 (South, around 240°)