Hair transplant: I am using nicotine patches which are helping me not to smoke.

Nicotine patches may be better than smoking.  If you are concerned it is best to contact your doctor for recommendations.

Nicotine in any form (smoking, patch, chewing, vapor, etc.) causes blood vessels to shrink.  This can theoretically cause problems with graft take and healing.  I'd suggest you bring this issue up with your surgeon prior to surgery.

Anything that will help you not to smoke after a hair transplant, including nicotine patches, will be fine for you