Just for clarification: Terrestrial FreeView signals are broadcast on completely different frequencies to FreeSat transmissions, so you can't connect a Freeview box to the lead from the satellite dish.
As Ethel says, if you want to use the satellite dish for free TV reception, you'll need to get Freesat. The price for this is �150 including the dish, installation, a set-top box and the FreeSat card. If you've already got a Sky box you can buy a FreeSat card for it for just �20. Unfortunately, you seem to be 'stuck in the middle'. The �150 price includes things you don't need (i.e. the dish and installation) but the �20 price requires something you haven't got (i.e. a Sky box). You could try contacting Sky to see if there's a way to buy the box and card without the dish and installation but it might be easier to buy a Sky box from eBay and then just pay �20 for the FreeSat card from Sky
Chris