Your TV will be able to work in three different ways.
1. It can act as little more than a viewing screen (with an amplifier and speakers) when it accepts a signal from an external source (such as your Sky box). i.e. it will be the Sky box which will be 'doing all of the work'.
2. It can receive a signal through an aerial, which is then handled by the TV's built-in digital tuner before being passed to the 'screen + speakers' final bit of the circuitry.
3. It can receive internet data from your router, which is handled by the TV's 'built in computer' before being passed to that final (screen + speakers) bit of circuitry.
Those three systems are distinct from one another, so can switch from using your Sky box (but, if you want, leaving it to record something at the same time) to either terrestrial TV (assuming that you've got a normal aerial, of course!) or to internet use. The Sky box won't interfere with the other uses (or vice versa).
However, if I've read the information here correctly
http://www.samsung.com/uk/internet-tv/
the TV's onboard computer (for handling internet data) doesn't have a web browser, per se. It just has certain apps built in (such as those for accessing the BBC iPlayer or Youtube videos), with further apps being available to download. So (as I understand it) you can't go to ANY web page (such as Facebook). You can only access the websites which the TV has dedicated apps for.
Chris