I used a laundrette which has smokers outside but room well ventilated. smokers also come in to use the tumble driers. dust on the tumble drier and my clothes fell in this dust for a short while. is this a danger to my health from the 3rd hand smoke?

Risk here is hard to estimate. Your lungs have a self cleaning method that traps and removes environmental dust/pollen, smoke and other debris. That system is overwhelmed in smokers and people in occupations like coal mining where the particulate is pervasive. I would not spend much time worrying about this type of exposure and just avoid what you can.

Only breathing in smoke itself can cause lung problems. Second or third hand smoke in a closed environment if breathed in over a long period of time will cause problems. Wear a mask like you would for COVID or just stay away from smokers.

What you described is not likely to have any meaningful effect on your health. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV, Flu and Covid vaccines. Wish you good health!