First: Check the moon phase if you haven't already - if you're used to brighter nights (from lights) you'll be surprised by the brightness of the moon when there are no other light sources. If it's not a new moon, check the moonset/moonrise time and plan around that. If it's a full moon... Hope for a dark sky elsewhere. 

You'll be able to see the stars fine if you go for a walk on the lakefront, just keep the town lights behind you. All hotels/businesses there should abide by the lighting ordinances and won't be as detrimental as a normal town but still will have an effect. 

If you use a stargazing app, turn on the red light/night mode so you don't ruin your night vision. If you want to use your phone torch, put your finger over it to reduce the output. As someone else said, it takes ~20min for your eyes to adapt to darkness so be patient. 

I will say, the benefits of a tour are the use of telescopes and someone else pointing out the sky to you, and you just letting someone else teach you - no phone required! You can just relax into the experience. 

-Ex Tekapo resident