Just in case there are people waiting for an affordable 4G home broadband solution, Three are currently offering 100GB a month with the Huawei B310s-22 LTE router included for £30 a month on a 12 month contract.
Their website only has the 40GB plan for £24 (which isn't a bad price, but is a bit low on data for me). The 100Gb is available in-store however. Apparently, the 100Gb offer is not available in some areas (presumably their backhaul wouldn't cope in some locations) which is why they don't offer it online.
I'm now using this in combination with ADSL Max - load balancing between the two using a Vigor 2860n+ . The ADSL give me a static IP, the 4G gives me a welcome speed boost (particularly upload). So far it is all working nicely.
BTW the router is unlocked, so could be used for other networks.