I bought an 03 Civic LX and there is a blown head gasket, mechanic recommended I go to a machine shop and get it resurfaced. A few weeks ago I was driving and noticed it overheated at idle but when I was up to speed as long as i had the heat on full blast it would stay around the center, I had to drive about 10 miles and around 20 minutes like this as there was no safe place for me to pull over. My question is do I need to get my engine block resurfaced along with my cylinder head?

 

Generally no but there are machinist tolls that can tell you how bad it may be or whether it's within tolerance , your experience may differ .