I just looked at Vodaphone as the cheapest available and they want a £60 connection fee to run a line. I'm not complaining I think that is cheap for a company to arrange but I have no idea what they need to do. Do you?
£60 is fairly standard, it is what BT Open Reach charge to activate a line; if a new physical line is required the fee goes up - mine was £80 over 5 years ago, when BT were charging ~£150.
Dont forget, if you leave them, there will also be a termination charge and a connection charge for the new ISP - although some of the big players absorb this into their costs and/or offer to pay your termination charge for you..