Ive read up a bit on the term, but still not sure exactly who they are.
Can someone, in layman terms expain exactly who/what they are?
(is that a loaded question or what! LOL)
Wahhabis follow a very literalists and puritanical form of Islam that they claim is the pure and uncorrupted Islam of Muhamad and the first generation - the Salaf - which is why they are also called Salafis.
It is the state religion of Saudi Arabia and has spread all over the Muslim world influencing every corner - though they are not by any means the majority - they do tend to be very vocal and active.
Yes they certainly support Shari'ah Law and see it as the only legitimate rule of law for mankind and seek to implement it wherever they live - though unlike the group known as HizbuTahrir (and al Muhajoroun) they don't see this as a top down process (i.e. topple the state and replace it with a Khalifah) but a bottom up process, as in they want to
bugger everyone change people through Da'wa and hope to change the society that way.
In recent times the two militant movements have largely merged in the UK and are often indistinguishable.