Tank battles take up a lot of space. If you think of the great tank battles of the 20th centenary (they where invented in 1914, and there have not been any this century!), you will see that the battles took place over large distances (except WW1 battles because the tanks where so slow!).
Famous battles to research are: British 8th Army and Rommel in North Africa, Battle of the Bulge in Europe, The 6 day war in Israel, and Desert Storm in Iraq.
With these battles in mind, you may want to double the gaming space you usually use. An 8 foot by 12 foot table may be best.
The Spearhead rules allows you to have an extra choice on the organization chart. This extra choice can must be made up of one of the formation types defined in the Games Workshop website Article.