It's really a close call in this case. The Intel 520 is stronger than integrated graphics chips have been in the past, but still limiting and yes the processor is very borderline for TS3. If you have no stronger system on which to play, you might want to proceed very cautiously with guarded optimism and try the base game only. Or the base game plus HELS, the Stuff Packs don't add any real overhead to the game. LN and Uni will each add more stress, so don't install everything all at once in case there is a tipping point right around there.
Seasons would probably put the laptop on overload but as @puzzlezaddict says, different players have different experiences on borderline capable systems. And the prospects for long-running, overly complicated ongoing games with lots of added content or running on anything more than lower graphics settings in the Game Options might be a bit slim, I'm afraid.
