As for getting a BT line, they are usually quite willing to install one (for around £125 fee) with a basic monthly rental of around £12. They may require you to put down a deposit of several hundred pounds until you've shown you can use responsibly.
Many people nowadays do away with a landline until they have set down roots (i.e. know they are going to stay in a property for some time). You can get a USB modem for mobile internet from all mobile operators from under £20, with a monthly charge of around £10 for 1GB download limit, with no contract.