Sapphire 4x4

When i let the car idle for 30 secs or so then pull away i get a quite substantial pile of blue smoke in my rear view mirror But as i continue to drive on theres no more and its still pulling fine. Sometimes going around a roundabout in second then pulling away it does it again. Ive been keeping a close eye on the oil level and that doesnt seem to be dropping any more than normal but i dont realy do that many miles in it. Im not that clued up on in depth engine knowledge but i can grasp the basics Any help or advice on what to do would be much appreciated. Cheers