Hi all, 
First timer doing some minor reno works here.  
I'm planning to rewire my master bedroom, e.g. add more socket points, lighting points. For the attached toilet, I intend to change the toilet bowl, basin and heater, add some shelves. 
All the lights and toilet stuff are bought and pending delivery. 
Now, the question is, should I get a plumber and electrician to do each part separately? Or should I look for a contractor to take care of both? 
Also, do I need to get approval/permit from HDB for the rewiring and toilet works?