I've only recently joined sky with 3 basic tv packs and this morning got the above email offering me the rest of the sky TV package for free for one month.

Now i really don't want to be paying for any extra packs by not being able to cancel due to having to give a months notice.

Reading the small print quoted below,

Offer terms: Free 30 day upgrade to Sky World (6 Entertainment Packs, Sky Sports Pack and Sky Movies Pack currently 51.00 a month) Trial is available to customers who join Sky TV and subsequently receive this email. During trial period, you continue to pay your current subscription amount (19 - 24 per month, dependant on your choice of Sky TV packs). At the end of the trial, you will continue to receive Sky World and pay 51.00 per month for this. Unless you let us know before your trial ends that you want to change your subscription packs. After the trial period you can make changes to your TV package inline with your TV contract (this requires you to give 31 days notice to change your package). Only one offer per household. We will aim to update your Sky TV viewing card within 48 hours of registering for this offer. If you choose to change your Sky TV packs during the offer period, the offer will end and standard prices will apply
it looks like as long as i call up in the trial period it'll be cancelled straight away. Or do i need to call up to cancel on the same day i activate it via the link in my email?