Hi Nigel.
If you add sugar/honey that is going to make the cider stronger, and won't help with the tartness. The honey might leave some residual sweetness, but will take away from the taste of the apples. You can add some splenda or something when bottling, but the best thing is to leave the cider condition for about 6 months before drinking it, and it should be really good then. How long did you wait last time before drinking?
Cheers,
Billy.