Ride Newquay, St Mawgan, Padstow, Camel Trail to Bodmin, old A30 roads to Mitchell, NW via St Newlyn East back to Newquay.
Camel Trail Padstow through Wadebridge to Bodmin is absolutely fine on a road bike and recommended. Trail NNE up the Camel valley is a bit rougher but still OK on a road bike (YMMV). Last 15km of Newquay loop linked above is hilly and mostly minor roads (see advice from
@13 rider upthread).
Note there is a ferry from Padstow to Rock if you want to go further NE and avoid A39. Also the coast road both NE to Padstow or SW via St Agnes and Portreath to Hayle is a great, if challenging route.
Finally consider going S via the B3275 and Probus to the Roseland peninsula and take the King Harry ferry across the River Fal to Trellisick, then W via Carnon Downs and N past W edge of Truro to Zelah and back N to Newquay.
Keep away from A30.
Have a great time.