We have two large cedars in our front garden that are turning brown - is this normal - should we cover them - is there some nutrient they are lacking or have the caught some disease?

There was an awful lot of browning on the "inside" of cedars this fall. This is a completely natural phenomena, called flagging, that they go through every year. If the browning was on the inside, and not out to the branch ends, it's likely OK. We had dozens of calls about this very thing in September and October. Make sure the ground is well-watered before it freezes, so there is moisture available to the cedars if they need them. Fertilize with an evergreen fertilizer in spring, and they should be fine.