Unlimited Fibre broadband from plusnet is 25 per month if you pay monthly or 22.50 if you pay line rental upfront, if you factor in the 70 quid quidco you'll get it for around £19 per month or £17 if you do line rental saver.
I've moved from BT because of the recent price hikes and will be saving myself £9 a month even without the quidco.
12 month contract
Plus £25 activation fee
+ Installation charge of £49.99
Installation charge only if a new line is required