You can't get Sky Sports channels without paying for them or breaking the law. Sky (and other providers of subscription services) have been making a great deal of progress lately in prosecuting people who offer to help people bypass subscribing and also in closing down access to illegal services.
So, if you're tempted to go down the illegal route, you could
(a) find it far more difficult than it used to be to obtain a suitable device ; and
(b) end up paying for something which quickly stops working because the streaming services which were feeding it have been closed down.
Sky Sports channels can be obtained through BT, TalkTalk and Virgin Media packages, although they're not necessarily cheaper. (It depend upon exactly what you include in the bundle of services you sign up to).
They're also available via Now TV (which is owned by Sky).
See here for all of the available (legal) options:
https://www.choose.co.uk/guide/get-sky-sports-cheaper-deals-offers.html