you would need to replace the LNB (the bit on the end of the pole that sticks out the front of the dish) with one that would give you two separate feeds and run another cable down from the dish to the TV.
yes, it will have two feeds going to the back of the sky box, if you want to continue to use sky+ to record and watch different things you will need to keep the 2 feeds going to the sky+ box though.
With a bit of luck they will have supplied you with a quad LNB when they installed the sky+, in which case you just have to run another cable from one of the spare outputs on the LNB to your new TV.
BUT the Freesat system doesn't carry any Sky channels! It competes with Sky, albeit broadcast via the same Astra satellite cluster and using the same dish and LBN as for Sky.
Forgot to say, if Sky fitted your Sky+ (rather than a local shop) then they ALWAYS used a Quad output LNB. You can just run a cable from a spare port on the LNB to your Freesat enabled TV. Be sure to use a waterproof boot or self amalgamating tape to make the LNB connection waterproof.