I know my local unit which has the same times as the general hospital its attached to is 3-4pm and 6.45-8.15pm but I know that doesnt help you.
If you have visitors that can't come any other time and need to bring u18s with them you can arrange to see them in the guest room. This has to be by prior arrangement in my local unit. Literally, a room with chairs and the staff will look in the door every 15 minutes minimum.
We cant see visitors in our rooms or anywhere beyond the nursing station, however there is a mens lounge, a womens lounge, the dining area, the quiet room, the courtyard with seating in various spots around it (its part of the unit but can't go anywhere from it), a small courtyard but need to be let out to it by staff and it has a garden bench, the main TV room which has sofas with enough seating for 20 (the ward capacity), the foyer area which has armchairs so we all have space to see people without being crowded into each other.
If visitors bring you in any stuff, it has to be checked by staff before you can take it back to your room to make sure its safe and not something which you shouldn't really have.
Last time I was in a friend send me a present via amazon prime to cheer me up, I was taken into the OT room on the ward to open it with the staff member as needed scissors and so they could check it was something safe for me to have. It was a teddy. They took the packaging away and left me it and the card.
Same as when on a leave pass, I had a list of stuff to get for other patients and their money and receipts all added into their various envelopes to return back to them. Other patients when going on passes did the same for me and we all helped each other.
Can I suggest if you would like to bring your friend something, that you take a Get Well Card along with you. They are a common sight on medical wards and a rare sight on MH wards. MH is just as valid as you will appreciate. I often bring/send to my friends on wards and they have said they get a lot of comments about them as they are the exception rather than the rule.
I've spent a lot of time on psych wards in my life, At one point I spent on average 6/8 months of each year inpatient over approx a 7 year period. That's a lot of time. I stopped counting how many admissions I had once the total reached 30 as it was bringing me down but there was quite a few more.
At one unit I was on there was open visiting from 2 pm each day till 8.30pm. It was absolutely exhausting as it was in bays of 4 at the time and there was a constant flow of people in and out and even if I had visitors, I often sat in silence with them or they held my hands and stroked my head quietly which often got looks from some visitors but it was what I needed and I had nowhere to shut down from constant stimulus which was hard. The unit is now all single rooms with ensuites and can go to the room at any time, however, the door has to be opened slightly so staff can see in without disturbing you as the doors constantly creak otherwise.
if you get thru to the main switchboard for the hosptial they should be able to tell you without having to go thru to wards etc