grant_k: I am on the most basic Sky plan there is, costing $46 per month and I get TV1/2/3 all in HD.
Wasn't there a $26 or so basic plan a while back for those who could not receive TV1 etc, which essentially mimmicked freeview. If that was still going, you'd probably get the channels in HD still, and minus the basic sky channel offerings, which you may or may not actually want.