Impossible, you can get a freesat box which you can just plug in sat cables and will work but a freeview box will only work with an aerial. You can also just use the skybox as a freesat box once you stop subscription it will still allow free to air channels to be watched.
That's freesat not freeview, you want a Humax box, £80 for a basic one or £200 for one with a built in hard disc recorder, or if you're ditching Sky, your Skybox will continue to work on the free channels but Sky+ won't work. Alternitively buy a new smart tv with integrated freesat, freeview and streaming £400-500 should get you a reasonable one.
Take a look at this Log in to Facebook | Facebook It's all streamed content and it's installed on an Amazon Firestick Totally portable,take it with you anywhere you just need an internet connection and a tv.buy the firestick £40 to £50 get the app installed on it and then it's £50 a year for the content.Do yourself a favour and look at it you won't be disappointed