They're not fussy about soil ph, so any potting soil would do, but if you want it in a pot long term, use John Innes No. 3 for preference, or a mix of John Innes and mutli purpose to make it lighter.

and before you buy it make sure you can smell it. I cant smell mine and others are saying the same. So sniff before you buy ;o)

Thank you for your advice,will do as you say,hope mine smells.

interesting about smelling before you buy. my 4 year old shrub flowers every year but I can never smell it in the garden even close up but I cut some sprigs to bring indoor and the warmth of the room brings out the smell but its quite overpowering at times.

Strange.

Um. I can smell mine but not very strongly but I thought it was just something to do with me having done something it didn't like..

BarbaraK makes a good point - all fragrant flowers emit more scent when the weather is warm, or when they're in sun, which is why the scent is much more noticeable indoors. So if your Sarcococca flowers outdoors when the weather's as cold as it is now, you probably won't catch any scent from it at all...
Some plants with fragrant flowers do vary in the intensity of the scent though - I had a Philadelphus years ago that always flowered, and had no noticeable fragrance at all.

My best winter/spring scented flower is a skimmia. I can smell that from a few yards away. My sarcococca is in shade and never sees the sun during the winter but as I said always flowers. I may try one in the sun and see if any difference.