if you have only 13Mb/s adsl, it might actually be worthwhile looking at mobile broadband and porting your number across to VOIp via say Andrews and Arnold.
Three do an unlimited data for £20 a month amd A&Ado a VOIp service for around £2 a month.
All of the mobile netowkrs can typically get up to 45 Mb/s but if you are in the countryside you may need an external antenna