The best cable on the market is PH100 Cable Sky Endorsed for analogue and digital or PF100 Coaxil, which is Gas injected, foam Core this is the best for High Speed Data Transfer CIA approved. This is what we install in all our house - Smart Home Builders. You can pick this up from most TV wholesale companies.
Or try h**p://www.screwfix.com i think its around £25.00 for 100m