Basically what Radgirl highlights above - urologists/endos can't agree on this so what chance does the CAA have and for us pilots who wish to increase the quality of our lifes with normalising our hormones have to go through the process... Alot of UK specialists who operate in the NHS use their guidelines which basically means you have to be really clinically unwell to be diagnosed with hypogonadism, its much lower limit than the BSSA for example and our american friends. For the CAA purposes, If your on treatment, then it needs to be reviewed and under the care of someone that knows what their doing - this is probably the case for the vast majority of medical issues, but for us it typically means it will cost more. Theres a couple of great clinics in the UK that know what their doing and will give the medical oversight that CAA require, but its not as straight forward as it ought to be sadly, with the CAA.
Your first hurdle with the CAA is a diagnosis letter which follows the BSSA guidelines on testing etc. When you commence treatment, I was told 4 weeks minimum of medical suspension. It was basically "4 weeks on stable dose". Trouble with any TRT protocol is you start on given dose and after 6 weeks or so your bloods are taken, then its adjusted and the refinement begins to zero in on your optimised dose. So your dosing will change unless your very lucky. So plan for a longer downtime, i.e. 12 weeks+. I also agree and wish male HRT was viewed as the same as female HRT but I guess normalising your hormones is seen differently between the two sexes and I suspect its down to the anabolic abuse with the CAA wanting your numbers monitored (i.e. high numbers do lead to cardio risk, so it sort of makes sense in a way) but it could be easier to get onto it but with the required oversight.
I wouldn't recommend anyone try TRT unless its under the care of someone who knows what they're doing (i say this as theres many online providers popping up left/right and centre who would diagnose and treat your dog). It should be viewed as a potential life long treatment plan if it helps you and once your stable on any dose then bloods/paperwork confirming your all ok is academic.