One solution is to ditch a fixed line entirely. Sounds a bit dramatic, but can be less of an issue than you might imagine. One of my family cancelled their telco account here in Ireland, shifted across to a cell only. Three (Hutchison) have SIM only plans where you have NO monthly contract. Your €20 topup (Ireland) or, just looked, the equivalent is £35 in the UK, eeek... gets you unlimited "all you can eat" broadband at 4G speeds. Now that's intended for the SIM to be inserted into a cell handset. You could of course keep your handset plugged into charger 24/7 and "tether" to it from your PC. Or if you didn't care about using it for voice calls and texting, say if you've got a cellphone already, then you could buy a 4G router (around the 30 to 40 quid mark).
Pros / Cons
standing charge -
typically high speed +
service level guarantees +
no fixed charge +
minimum topup -
little guarantee -
speed depends on location -
They seem to have had good experience using it for last 4 or 5 months. A low monthly top up, no more standing charges, really decent speeds.
If you actually don't need unlimited, then you can top up for £15 or £20. Going on vacation?, just don't bother topping up till you get back... you'll still be able to access the top up part of their network even when topup has expired.
Anyway, hope that's of some help.
Best of luck with it,
(ex Network Engineer for a big frakking telco, long time RPG fan)