If you are not on cable, are you sure your local telephone exchange can provide 50 Meg ?
BT keep sending me offers for higher speed connection but the exchange can only support just over 2 Meg. There is no point paying for a high connection if your lint can't support it.
The first 18 months I was connected to the Internet I managed to get for free. I just kept changing providers who offered free trials.
When I was with BT I just cancelled my contract once the 12 months had expired and then signed up again at introductory rates. (I have 4 free modems lying around somewhere)
At the moment I'm with TISCALI. Yes I know they don't have a brilliant reputation but I have never had a problem. My connection is the same as BT, doesn't seem to have any download limits (might drop the speed during peek times) and at only £14.99 a month including line rental, is considerably cheaper.
It pays to shop around.
When I left BT and changed line suppliers, I keeps receiving letters from them reminding me that it would cost about £120.00 to be re-connected.
Someone called me from BT to try to get me to change back to them and they offered to reduce the connection fee to £100.00 if I did.
When I pointed out that I would save the cost of line re-connection in the first 6 months, the guy went very quiet and I haven't been contacted by them since.