Does it use data?
Yes, like any streaming service, watching channels over WIFI will use your broadband data.
Check your plan's data allowance with your Internet Service Provider (ISP) if you're a heavy TV watcher.
And if you're unsure or have a limited data plan, you might still choose to connect your TV to an aerial to minimise data use.
How much data will you use to stream channels?
That depends on the quality of the streams - learn more here.