As BatBoy says.
Of the big ISPs though, only Plusnet. They charge £2.50pm more than the advertised figure, plus on most if not all of their packages there will be an installation charge that they absorb if you take their line rental. It's all fairly clear on their website if you click the Broadband only button. It will still say line required but that's obvious, and doesn't mean theirs. None of their introductory offers will apply - they are all for broadband plus line.
Smaller decent ISPs well known on these forums that allow it are Aquiss, uno and vivaciti. Their prices tend to be a bit higher but you may not need "unlimited" at first. It depends if you want to jump straight into catchup TV, films and YouTube etc.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
My broadband basic info/help site - www.robertos.me.uk.
Domains, site and mail hosting - Tsohost
Connection - AAISP Home::1 80/20. Sync 59546/15321kbps @ 600m. - BQM