The visitors opened the scoring in the 10th minute when Mclauchlin powered over in the corner.
A penalty from Tom Ratcliffe reduced the scorers before the visitors doubled their advantage with a try in the opposite corner.
Young winger Tom Anderson then opened his account for the season with a try in the corner to tighten the gap at 10-8.
The visitors capitalised on a Scarborough error in the 38th minute to stretch their lead to 15-8.
Man of the match Ratcliffe brought the game level after half time when he ran through the defence and crashed over the line.
Both sides then exchanged kicks at goal to bring the game to, 18-18 going into the final 10 minutes.
With just minutes remaining, Heath snatched a victory after they piled on the pressure and scored in the corner.
The conversion was successful and the game finished 25-18 to the visitors.