Nerve sparing means you have a chance of recovering erectile function. These nerves are nothing to do with sensation in the penis - that's not usually significantly impacted by prostate cancer procedures (biopsies and brachytherapy can impact that, although it's rare).
The important thing about penile health is not to go for too long without erections. If you can't get them naturally, then you should be doing so artificially.
Things it's worth trying at this stage are the higher dose PDE5 inhibitors (20mg Tadalafil/Cialis, or up to 100mg Sildenafil/Viagra). These won't give you an erection just by taking them - you need to get aroused too just like before.
If these don't work yet, or you can't get enough for at least 3 erections/week, then you need a pump too.
The other thing that's useful is to get on to regular Tadalafil for which there some evidence it helps nerve healing and preserving penile health with reduced numbers of erections. This is either 5mg daily low dose, or 2 x 20mg/week (which can also double up for trying for erections as above). Even if this dose doesn't generate erections, it improves blood flow in the area which helps with healing and preserving penile health. (None of the other PDE5 inhibitors have this extra effect, because they are too short acting.)
If you have a knowledgeable/helpful GP, they may be prepared to prescribe these for you in the absence of a timely ED clinic appointment.
You could also ask your CNS if they can schedule an appointment directly with a pump clinic for the pump - that may have a shorter waiting time than going via the ED clinic, since they're run by the pump reps. Some ICB's require all pumps to be prescribed via a pump clinic because it doubles the chances of using it successfully afterwards, and they only regard them as economically viable in such circumstances. The ICB covering Berks, Oxon, and Bucks has an ICB-level ban on supplying pumps.
Just to add to what Lyn said, for the SomaErect Response II, you also want the spare Surefit rings, which is NHS code 15222, as only one comes with the pump. These are only used for sex, not for penile rehabilitation, and it seems far fewer men find the pump useful for sex than do for penile rehab.
I have heard one of the Bathmate models is also available on prescription, but I never heard of anyone who got it that way. Most areas only offer one and if they use the pump clinic run by the reps, I think that's only the SomaErect.