Thanks Scott but I've found out what it is now. I have ran a line test (I know, not supposed to) and there is a loud humming on the line. Not sure what it could be. Maybe someone has bugged the phone line? 
Edit: Upload and download speed are low as well, not from a speed test but in the router setup page it says my downstream speed is 600kbps and the upstream speed is 117 kbps. This isn't the first time, just the first time I have posted it on here It happens occasionally on a weekend, the internet goes really, really poor like 1500 ping and failing to load some websites but not others etc. Really strange. I am on the Talk Talk forum but they can't seem to pinpoint an issue.
Edit: Upload and download speed are low as well, not from a speed test but in the router setup page it says my downstream speed is 600kbps and the upstream speed is 117 kbps. This isn't the first time, just the first time I have posted it on here It happens occasionally on a weekend, the internet goes really, really poor like 1500 ping and failing to load some websites but not others etc. Really strange. I am on the Talk Talk forum but they can't seem to pinpoint an issue.