Try the software (router stats lite) in my post, I use it to monitor how stable my SNR is, if you see problems with it then try to sort things out on the line, if not and your speed is good then don't worry till you can afford it
Failing that call Sky TS any time after 8pm most nights and you will have very little queuing to get to tech support and after 10 we can normally get straight through to Customer Solutions Team for Tier 2/ 3 assistance.