I have been through this surgery, and others. I have done quite a bit of research prior to all my surgeries. If you have a specific question, feel free to ask.
To be clear, this is major surgery and is not to be taken lightly. That being said though, I've heard that Charring Cross is a very reputable hospital and its staff is highly qualified.
I'm sorry, but I don't recall any of the surgeons names that perform GRS operations but I wouldn't worry about the surgeons skill. There is a Dr. James Bellringer there that performs vaginaplasty but I am unfamiliar with him.
Also your fathers age is really not an issue providing she is otherwise in good health. I assume this is true as she has her surgery scheduled and that would not have happened if she had any health related issues.
I personally know a woman who had her operation when she was over 65 and she came through with any problems whatsoever.
One thing you can do for her is to accept that she is a woman and would really appreciate being referred to as such. She is still your father, that can never change. Neither can the love she has for you. It can be awkward calling a woman "dad", so maybe you might want to start calling her by her feminine name. My kids still call me dad and I have no problem with that.
This site has many descriptions of how Gender Reassignment Surgery (GRS) is performed. There are a few different approaches. The most common is called penile inversion.
In short, the shaft of her penis will be removed, inverted, then inserted in a cavity created by the surgeon to create the neo-vagina in the perineal raphe . This will be just above the anus. If necessary, additional tissue can be used from the scrotum to add depth to the vagina if needed. The testicles will be excised and discarded. She will be permanently sterile following the operation.
The glans, or head of the penis and the associated nerves, will be paired down to form the neo-clitoris. It will then be put into a space that was created by the removal of the penis. The urethra will be shortened and placed in the space between the clitoris and the vagina which will allow for common feminine urination.
The remaining tissue from the scrotum, if any, may be used to form the labia minora and clitoral hood. The labia majora will be formed from tissue around the penile site. Some months following surgery, she may want to have some minor cosmetic surgery to better define the appearance of the outer genitalia. Though it is not a requirement.
Once the neo-vagina is in place, a stent will be inserted into the vagina to start the healing process and prevent the vaginal entrance from healing. Following her healing, she will have to dilate her vagina multiple times a day for several months following her surgery. And she will have to continue dilating at least once a week for the rest of her life.
She will have a very good chance of having vaginal and clitoral orgasms once she heals. Though there is a very slim chance that she may not have any sensation there at all.
There can be complications from the surgery as there are with any major surgery. The one most worried about, but actually least occurring is a recto-vaginal or bladder-vaginal fistula. That is an opening between the rectum and the vagina or the bladder or the vaginal. These are very serious conditions as they can easily cause infection. As I mentioned, though, they occur extremely rarely. For the most part, as she heals her risks for complications become less and less. A few weeks following surgery, she should be able to start physical exercise again.
This surgery is very important to her. And really she has already done the hardest part. Transitioning gender is the most difficult thing a human being can to. It causes you to possibly sacrifice EVERYTHING in your life.
This is not done on a whim. It is done to save a life. Being transsexual is a terminal condition and one that she has had all her life. Eventually the stress and depression of living the lie of your birth gender becomes so great that suicide is the only other option.
You said that her family has all but deserted her. That shows how much your father needs to transition. She is willing to separate herself from everything else in her life to live true to herself.
You also mentioned that you were worried sick about the operation. She probably felt that the only options she had were suicide or transition. Ask yourself which would you rather have, memories of a dead father or a living parent that has endured tremendous ordeals but underneath is still the loving father you knew.
I wish you all the best. Please keep us posted. And if possible have her come to the list as well. We'd like to hear from both of you.
This is probably the best list on the Internet for information about transsexuality. We have many caring people here who want to help others. Feel free to ask any question we'll be happy to answer.
Also if you get a chance, please introduce yourself in the introduction forum and review the site guidelines.
Really, hon, everything will work out fine. We'll keep you and your father in our prayers.
-Sandy