“Do I have leukaemia”

Not necessarily with this information. I recommend you see your primary care physician for an evaluation.

rash in legs, bruises on arms, achy knee are very general symptoms that can happens from dermatitis, petechia due to aspirin and arthritis. You need to see your doctor, order CBC with differentials to see anything is abnormal or not. Check you r TSH and free T4 to make sure there are normal limit. These symptoms should not scare you, and you just need to see your doctor and do the test.

Unlikely. A simple test CBC sometimes can evaluate possibility of leukemia.

Your symptoms can be seen in many disorders, both benign and malignant, so we cannot diagnose leukemia based on them. If you are concerned you should see your primary care doctor who will order a CBC with differential to see if the blood counts are abnormal in a way that might suggest leukemia. You would then be referred immediately to a hematologist if they did suggest a bone marrow problem such as leukemia. At times unexplained bruising can be from conditions such as iron deficiency which is easily treated.. your bruising could also be contributed to by the aspirin you take. Achy knees can occur in many conditions, many of them benign. Again, I would start with some blood work with your primary care physician.

Unclear, but needs work-up. See your PCP.