To the OP – I’m connected by a roof mounted 5G/LTE directional antenna and a mobile router.
The 4g routers can be had for £150 or so but worth trying a couple of network sims to find the best speed / reliability.
If you’re using a directional antenna you’ll need to know which mast to point it at – masts have different combinations of radio modules but the networks are fairly helpful in telling you which mast is where and what sort of speeds you’ll get.
Try and keep the cable runs short though – the gain from the antenna is eroded by a long cable run so if possible attach the antenna to a chimney and run the cable under a roof tile into the roof void.
After some trial and error my experience was:
Three – not the fastest but pretty reliable
Vodafone – occasional super fast speeds but more often than not very slow speeds and high packet loss
EE – always fast downloads (150Mbps to 270Mbps , uploads steady but reliable. I’ve had 2 short (hour or so) outages in about 6 months one of which may have been an automatic firmware update on the router.
Theee and EE both have a 1Tb fair usage policy (upload and download combined) which is fine for less than £30 a month.