Gallbladder and diastasis recti issues. Can this prevent me from getting a tummy tuck? Should I do the TT first?

Part of a tummy tuck is repairing rectus diastasis. Having your gall bladder removed is not a contraindication for a tummy tuck.

If you need gallbladder surgery I would highly recommend you have that first. Once you are healed from that you can have a tummy tuck performed, the advantage to doing it this way is that if you develop any hernias or scars that need to be revised they can be fixed at the time of the tummy tuck.If you have a tummy tuck first, the gallbladder surgery may cause hernias or other issues that could affect your result.
Hope this helps!

These are two completely different issues that should be addressed separately. And the gallbladder absolutely be addressed first. Hopefully they can fix this laparoscopically. If you end up with a large right upper quadrant abdomen scar from a gallbladder removal, it can affect the ability to do a safe tummy tuck. Once you were well, healed and symptom-free, then I would advise the diastasis repaired with the tummy tuck.

If the patient is concerned about having a TT wound (a transverse abdominoplasty scar), then there is the option of endoscopic abdominoplasty. Endoscopic abdominoplasty is a minimally invasive procedure that uses a laparoscope (a thin tube with a camera) to repair the diastasis recti and to remove excess fat from the abdomen. This procedure typically results in smaller scars than traditional abdominoplasty.