Tobu Ltd Exp rsvn a must to Nikko in Nov?

2 of us plan to visit Nikko for a night on November 2nd (Thursday). We will be coming in from Otorii (via Keikyu Airport & Toei Subway to Asakusa Toei Subway Station, perhaps from Otorii at 8.15 [ETA Asakusa 8:58am]) and catch the train from Asakusa Tobu Station. Looking at taking the 9.30am Tobu Ltd Exp train.
Is it necessary to buy online the Nikko City Area Pass and the discounted Limited Express ticket or being still midweek, safe to just buy from the Tobu Sale office at Asakusa before boarding the train? Is the Tobu sale office busy around that time? Should be depart Otorii earlier, perhaps 8:05am [ETD 8:45am] instead?
Since we will only arrive Japan the night before we won't have an opportunity to buy the pass and ticket from Asakusa on an earlier date.
Since we only have a night in Nikko we would like to optimize our time there by arriving the latest, before lunch, knowing sun sets before 4pm! Planning on visiting Kanmangafuchi Abyss (1st day after lunch) & World Heritage Site (2nd day).

Thanks,
Mel

Reservation, if you can get them is better than non-reserved, but there are other ways to get to Nikko (not necessarily cheaper.

You can do more than that on the first day - plus, the "abyss" is simply a nice piece of river (white water) with good marketing. While still avoiding the weekend, you could also go the the lake depending on the leaf viewing season.

This time I don't intend to go up to Lake Chuzenji. I did that few years back. Basically a friend (not been to Nikko) and I just planned a 5 night trip to Tokyo (Nov 1-6). It's too early for Koyo in Tokyo so I think Nikko will be nice. Read that it may be too late for peak Koyo up on the mountain anyway but good in Nikko town so thus, I've decided just to stick to the shrine and the abyss and perhaps the Imperial Villa.. Maybe if it's not too complicated, may visit Kirifuri Falls. I've already booked Nikko Tokanso Ryokan.

Just realized 3rd Nov is a public holiday ☹️

Also I just read cancellation of the ticket incurs minimal cost [\100 as long as before departure]. Thus, not bad at all if we ended up deciding on an earlier train or something..

ok - sounds like you have a good plan. The town is actually very nice with a lot of things to visit/see and I chose it for my own holiday last year (a few nights - I stayed near the "abyss").

Regarding the abyss, would you recommend we bring something to picnic there? Can you get to the waters' edge easily? When in the day is the best time to go?