Maybe MacMillan nurses are different in different areas, but mine set themselves up as the "go to" point for everything, and they're really good. They don't do the ED clinic, but they got me the appointment, much faster than my GP would be able to because they know the ED nurse who does it. Likewise, they organised Tamoxifen within 24h of me requesting it by getting a prescription from oncology (who I'd never met at that point). I'm sure they would know exactly what to do if I asked for sexual or relationship counseling.
A couple of weeks after diagnosis, the MacMillan nurse offered a Holistic Needs Assesment (HNA). This is a form (I don't have a copy now) which has a list of perhaps 50 different concerns you might have ranging from sexual function, to body image, to money worries, to losing your job, home, etc. You tick off the ones that are a concern for you, and they go through those and get you the relevant support. My GP also wrote to me at the same time and strongly recommended I do the HNA when it's offered. I didn't tick off many, but I was concerned about future ED, body image, and how to continue being a carer for my parents. As part of going through this, they got me the ED appointment even though I didn't have any ED at that point, but it enabled the ED nurse to go through the issue with me, and they would have prescribed the 5mg Tadalafil if my GP hadn't done so the week before, and they invited me to come back the moment I start having any problems. The MacMillan nurses have been present at my initial consultations, and afterwards check if any of my concerns from the HNA need addressing, for example if some treatment was going to be an issue with caring for my parents.
I have found they are always happy to talk if I pop in anytime (might have to wait as they're often with other patients). They are also the constant as you get passed between urology, oncology, scanning, etc.
If Langers has such a resource available, do go and make use of it. Might be an idea to ask if you can do a HNA if they offer it too.