I use 3 network with a
mifi, £15 per month for 10gb, on a rolling 30 day contract. It was the cheapest deal I could find about 6 months ago. Reception on the whole is pretty good, except in places where you wouldn't expect to get a signal, eg hilly remote areas, although I've been surprised sometimes to get a signal in such places when I didn't think I would.
Mifi sits on dashboard as reception in back of van isn't always great (metal body reduces signal strength) and i have a clear waterproof bag to put it on the roof in bad signal areas. The only downside to the
mifi is that its another gadget to recharge and
battery life is only about 4 hours. But its kept permanently plugged into cig socket in the cab and the
solar panel on van means there's no risk to the starter
battery.
Over the summer I had the EE 100 gb monthly deal for 2 months, free SIM, thanks to a heads up from Admin about this. The SIM was free, just required a £10 top up to activate the freebie 100gb. Was down south over the summer so got 4g signal, faster than my home broadband, and good coverage. Not sure how good the EE coverage is further north. I used the SIM in my mobile and hotspotted my laptop with it, good enough to stream live TV.
It seems that EE are offering a similar 100gb free sim Christmas deal so will try to get this although they may not allow it having had their summer deal.
I currently have 3months unlimited data with Vodafone in my mobile, thanks to a billing error - I complained about their error and this was their goodwill gesture to say sorry. Vodafone, like EE, allows tethering and hotspotting. Many other networks don't.