EE will not give out or confirm Mast Locations, you could try and ring Tech Support on 150 and explain your reason, you may get lucky and get approx info like west or north of your PostCode, worth a try.
A useful tool and App is CellMapper, which uses your Phone Info to Survey, Record and Vector Networks Masts and Signal Quality in your location, it's quiet comprehensive, again if your in luck other Users may have already Surveyed your Area, a good indication is if the Masts it shows are in colour Red or Green (Located) definitely worth installing and having a play to familiarise yourself with the App.
Finally you could use EEs Coverage and Status Checker for your Post Code as EE have now defined Indoor and Outdoor Coverage in Light yellow (Outdoor) and Dark Yellow (Indoor) and can sometimes be a bit of a giveaway on the Dark Yellow areas where the 5G Mast are roughly located.
Out of Interest what type of External Antenna(s) are you using? and typically high much Gain and how Directional are they, as different types of Antennas can work better or worse depending on Mast location and the number of Masts surrounding your location.
