Is a reading of 40 low for vitamin d and if so what type of health issues could it have on me for example could it prevent a fracture from healing?

Over 30 is normal --: Value of vit d. So your vit d is well within normal limits. Low vit d affects bone healing, causes tiredness, fatigue etc. Check with your gp, to ensure your general health is good ; also to confirm the reading of vit d, with your lab doctor, to ensure its within normal limits, as different labs do use different references, especially in different countries. So have that checked. Good luck.