>>> and won’t have to pay SKY, Virgin, Amazon, Netflix or anyone, anything
You might have to pay the courts quite a lot when you get fined for illegally downloading content though!
https://www.express.co.uk/life-style/science-technology/1116503/Kodi-WARNING-addons-fines-thousands-new-crackdown-April-20
https://www.edp24.co.uk/news/crime/norfolk-suffolk-police-to-send-warning-letters-to-illegal-streamers-1-6843524
Sticking to doing things legally, an Amazon Fire Stick comes with a selection of apps (and with others that can be downloaded to it) which add 'smart' capability to a 'non-smart' TV and which, depending upon what apps the set has already got, might add extra functionality to an already 'smart' TV. Each of those apps allows you to connect to a different streaming service but it's up to the providers of those services to decide whether or not you get charged for them. So, for example, the BBC iPlayer, ITV Hub and Youtube apps are free to use but the apps for Netflix, Disney+ and Apple TV won't be of any use to you unless you sign up to those services and pay the relevant subscriptions. (You pay the individual service providers, not Amazon).
However one of the apps on the Fire Stick is for Amazon's own Prime Video service. That's available to anyone who's signed up to Amazon Prime, which costs £7.99 per month (after a 30-day free trial) and gets you enhanced delivery options from Amazon as well as access to special offers, etc:
https://www.amazon.co.uk/amazonprime
'Amazon Prime' comes with 'Amazon Prime Video' thrown in:
https://www.amazon.co.uk/gp/video/offers
as well as Amazon Music Prime:
https://www.amazon.co.uk/music/prime?ref_=hawkfire_prime_detail_page_benefit_desc