@funkydunc – I used a site called cellmapper.com It shows the nearest towers and which bands/frequencies and possible speeds they require – also which networks they are open to.
I’m very lucky in that I live literally on one side of a valley and have many masts in range. Quite unexpectedly the cell tower I receive the strongest/fastest signal from is approx 12 miles away!
Theres one less than 3 miles away but due to its orientation the speeds I got were pants. As I say i’ve got from a 17mbps down and 1mbps up to ~70 down (on average, ive had this as high as 98 and low as 60) and a consistent 30mbps upstream.
I paid 150 for the dish but am free from line rental and the SIM is a fiver a month less than my BT bill was – speeds are literally 4-5 faster!