Glow Worm - Best Temp Setting ?

Hi All
I am new to the UK & have never had to use Central Heating before.
I have just moved into a new house that has a Glow Worm Ultracom hxi boiler. I have no idea what temperature to set it, as the manual says nothing (apart from the factory setting). I have been told that 67deg is good!!??? Is this correct, as I dont want it set too high.