Hi, don't know if this will help, as I'm not from the same place you are (I'm in Canada, and I've never heard of Sky except for the big blue thing hanging above us).
I was having the same issues with my new DLink DIR-615 router. Whenever the landline would be in use (cordless phone, however), I would loose my connection and it would resume the second (literally) I ended my call. I didn't have that problem before with my other router.
In my case, changing the channel on my router did the trick. I've found multiple posts about this. It was set to channel 6 and I put it to 11 and the connection now seems to hold when the phone is in use.
I don't know how you would do that on your equipment, but it may be worth looking into.