I have just found out I have gallstones. 2.8 - 5.4mm is there a treatment for this? Or is the only option surgery?

Surgery. At your age eventually you will have problems. Every patient has to be considered individually.
Yes. Surgery is the only option. The endoscopic approach is used for more than 90% of cholecystectomies today. Many are done as outpatient or overnight stay. Doing it electively lets you schedule it at a convenient time for your schedule. Good luck.