Can I join after having 1 kidney stone

Hi, I am afraid we are unable to give specific medical advice for individuals on this forum. If you are keen to join, you can consider the appeals process. If you appeal, try and provide a good argument for why you should be allowed to join - this may be in the form of a letter from a specialist detailing why they don't think your past medical history will cause you any issues in future. Unfortunately, sometimes particular medical conditions are a bar to service regardless. The most up to date version of the policy is unlikely to be available online, but you may be able to find an old version that has been released on a freedom of information request - it's called JSP950 leaflet 6-7-7. Best of luck.