Getting over the shock of diagnosis

Are you sure doing nothing is not a viable option? If the consultant is offering it I would presume it is. By day 3 of a diagnosis everyone thinks the only viable option is surgery, at day 3 no one thinks shooting cancer with a ray gun is going to cure it.

What you need to do is keep your mind open to all options. Read a lot of posts on here to get a feel of what life can be like after a cancer diagnosis. Realise that this forum doesn't have posts from the vast majority of people who were diagnosed treated and cured (about 70% of people) people without problems are unlikely to post here.

Once you have read a lot of stories on here, think about your own personality your own life and your own family and how each possible treatment may effect you. Your path through this disease will not follow the exact path of anyone else's disease, it just opens up your thinking as to what might happen, not what will happen.

At the moment don't narrow down your options. When you have your next meeting with a consultant you may have read about treatments offered on here which are not being offered to you, they may not be offered for valid medical reasons, but it could be just what is available in your health trust. Ask the oncologist about any treatment you are interested in, if they rule it out on medical reasons, move on, they almost certainly know best. Hopefully by the end of the meeting you will know the consultants thoughts, which may still be that all options are open. You will also know your own thoughts on treatment and possible side effects and then be in a better position to choose your treatment.

If we start considering surgery, some questions for your surgeon...

What are the chances of the procedure being nerve sparing (giving a chance of natural erections afterwards)?
What are the chances of good continence afterwards?

These questions can be answered based on the location of the cancer and your anatomy (things like length of membraneous urethra).

Does your surgeon do Retzius Sparing? (gives faster recovery of continence, but no difference longer-term)
Do you consider yourself to be relatively fit and not obese?

For radiotherapy...

Given that they offered you Active Surveillance, you are probably a candidate for any of the radiotherapy treatments, so ask what they offer:

The most common would be 20 sessions (weekdays over 4 weeks), possibly with short duration hormone therapy.
You are probably eligible for seed brachytherapy (unless prostate too large, over 55cc). That's a single procedure where 60-100 tiny radioactive seeds are placed in the prostate, a bit like the biopsy but significantly  less uncomfortable. This is sometimes done with hormone therapy. The seeds generate radiation for about 200 days before they wear out. They stay in for life, but are benign after 200 days. For the first 60 days or so, you can't have children or pets or pregnant women on your lap.
A new treatment as a result of the successful PACE-B trial is 5 sessions of SABR (a form of higher power external beam radiotherapy) delivered daily (usually split over a weekend) or alternate days, which is given without hormone therapy. The hospitals which were involved in the trial now offer this and NHS England has said it will be commissioned quickly at all hospitals which can do prostate SABR (which isn't all hospitals), but last I heard about 6 weeks ago, NHS England hadn't yet sent out the commissioning for this.
If you are not offered all these options, that's probably because your hospital doesn't do them all. Within England, you can be referred to any other hospital in England. This might be why you weren't offered a focal therapy too (although I'm not a big fan).

Most people consider radiotherapy as an easier option, but things like a long travel time for daily treatments can easily swing this, and any need for a long period on hormone therapy (not applicable for you). Radiotherapy is less likely to cause urinary incontinence, and possibly less likely to cause erectile dysfunction (although the data on that isn't reliable IMHO). It often does cause some short term bowel issues during or after treatment, and it has a small risk of causing long term bowel issues but with modern radiotherapy, the chances of those being serious are very low.

There's no one answer. You can have two people with identical diagnosis, age, etc, but other life factors would make them select different treatments.