Keeping this in view, can my doctor sign my provisional Licence?
You can ask your Doctor, although they may charge you £10 or more for the pleasure. I had a friend sign mine who was an Engineer, didn't know he could do it but they accepted it OK.
Also Know, can you use a short birth certificate for a provisional license? You can also use your original birth or adoption certificate as a form of ID, just as long as you also send in any one of the following: National Insurance card or a letter from the Department for Work and Pensions showing your National Insurance number. P45, P60 or pay slip.
Moreover, can I change my signature on my provisional?
Yes, you may change your signature whenever you want to but it should match your official documents such as passport, driving licence, bank accounts etc so that you will not have a problem proving that you are indeed who you say you are.
How do you send a photo for your provisional Licence?
You will need to send these along with a passport style colour photograph. Applications should be sent to DVLA, Swansea, SA99 1AD.