you can get a phone only but when you change your package it will start a new minimum term contract. ask yourself do you need a landline paying £19/month when you can get a mobile for £6/month with unlimited calls
you can get a landline number on a VOIP service for a tiny amount.
Pick up a VOIP phone for £20-50 on ebay and transfer the number to something like sipgate (free i think) and pay for calls. Or if you want unlimited calls its under £10/month. less than half the price of a landline