They are now known as 'Clinical Commissioning Group' when you applied it may have been called a Primary Care Trust.
Here are some links I have pulled off the net but a simple search of
"IFR COORDINATOR CLINICAL COMMISSIONING GROUP [ENTER AREA OR REGION]" Should help you come to terms with the general way things are done.
http://www.centrallondonccg.nhs.uk/medi ... 013-14.pdf
http://www.centrallondonccg.nhs.uk/medi ... 1.2013.pdf
What you are asking is almost impossible to answer in a forum like this. As areas have different priorities/budgets/ and sadly opinions (prejudice).
My gut feeling is if you have already had funding approved for a treatment. Then if you basically delay that and that money is not spent it may well be returned to the funding panel as unused and go back into the coffers. What you are talking about is not a couple hundred quid it is worth the paperwork to get it back. They also run from April to April as a rule (Financial Year).
Also it might land you in hot water if you are seen to lessen the value of this treatment.
Funding bodies when they come around to rubber stamping your application again in future may get cold feet and 'accidentally put you application to the bottom of the pile'. They are not a bottomless pit and if there is a choice between you and a 12 year old kid needing life saving surgery they are going to lean in that direction.
My view is if you have the funds, you are in good health. Then do everything you can even if you have to rent a bedsit opposite the hospital and get your treatment now rather than later as the way things are going it may not be there in future!
Don't give them an excuse to not fund you because if they even get a sniff of this you might be high and dry!
So your question reads,
"I was asking if the NHS can withdraw the funding that they've already approved for my lower surgery, as in do they have the right to take back their funding offer if I haven't completed the surgery within a set period (or for any other reasons), and ask me to get re-reviewed by a psych and then to re-apply for the funding? "
Yes this is perfectly possible. Although the problem here is less likely to be a Gender Clinic issue as they have already signed you off to surgeons. But the surgeon may wonder if you are stalling and hand you back to be reassessed as if you were keen you would get it done unless there is a MAJOR reason why you can't. Family death, you having a car accident and so on... Gap years, holidays, and so on are flaky reasons to me... Exams falling on the surgery date mean they may change the date if given sufficient notice. But what you are asking is a massive bureaucratic delay at almost every level and I would be concerned for you if you stall really.
Sorry, but again trans care is a Cinderella service and you may not get another chance to be in this position.