Yes, the museum itself is self-guided with displays and explanations in English; the guided tour is also available to minors, but of course, they won't be able to imbibe the "free" beer included in the price.

I suppose that if you know for sure that you are going to be there and you really don't want to miss out, I would contact them now and then re-confirm once a month .... at the very least, they will tell you the rules for making reservations. The website has contact info. If it is that important to you and you are unable to contact them by phone, pls pm me with all of the details as I have friends living in Japan and can ask them to call for you ....

O don't know the hours but you could e-mail or call them to double check the hours. Also they have a website that may list the hours of operation. Have Fun!

25Dec2017 falls on a Monday hence it is closed. But it is not a public holiday. Japan is not a Christian country, it merely treats Xmas Day as an observance day and not a national holiday. That means Tuesday is opened on the 26th Dec. Enjoy your trip!

If you are in a hotel have the front desk call for you, unless you speak Japanese it will be difficult otherwise. Enjoy!

The Beer Museum can be accessed by the "Loop 88 Factory Line" bus that stops among other places at Odori Station and in front of Seibu department store near Sapporo Station (departures every 20 minutes, 210 yen per ride). Alternatively, it is a 25 minute walk from JR Sapporo Station or a 15 minute walk from Higashi-kuyakusho-mae Station on the Toho Subway Line.

They have free dropping by and premium guide tour. If you prefer following a guide, you gotta pay at front house counter on the day you visit. Different languages with different time slots, and mainly in Japanese. No advance booking for entry to museum is required tho, you may try. If you want to visit the grilled mutton resto inside, you d better check out their opening hours on web and they seem offer package reservation at counter f.i.

The Beer Museum can be accessed by the "Loop 88 Factory Line" bus that stops among other places at Odori Station and in front of Seibu department store near Sapporo Station (departures every 20 minutes, 210 yen per ride). Alternatively, it is a 25 minute walk from JR Sapporo Station or a 15 minute walk from Higashi-kuyakusho-mae Station on the Toho Subway Line.

As Danny C pointed out, Beer Garden is not the same as Beer Museum which offers Japanese speaking guided tour. Alternatively you can read the English pamphlet, take the elevator to the top level and self guide as you come down. Depending on your interest, you can do it in an hour. You can enjoy beer tasting at the bottom level. 500yen will give you 3 beers. There is also ice cream for sale if you don't drink.