My director just let me know that my name has been put forward to attend full time second language training, for ten months, starting in two weeks. I don't know what to do. Do I say yes or no?

Here are my concerns:
a) it runs from 8am-4pm. Currently I work 7:30-3:30, so this would mean the boys would be in daycare longer, until at least 5, possibly later depending on traffic - the later it gets the worse traffic gets.
b) I currently telework one day a week, which is a luxury that I really love and depend on - it lets me do the laundry, do some tidying, keep up with things around the house that I'd otherwise have to do on weekends.
c) I've been going to the gym around 9:30 three days a week, and then working through lunch. If I took this training I could probably still go at lunch, but then when would I eat? To work out before work I'd have to get up at 4am, and I know myself - I won't do it after. I've committed to a year of gym membership.
d) I'm on the social committee at work and planning the holiday party, and I wouldn't get to do it.
e) I really like the people I work with, and I enjoy spending my day with them. At least one of the other five people who would be in this training make me crazy.
f) I'm not sure that I need 10 full months of training to get to the level that these people are aiming for - I have taken this language before so I'd be re-learning a lot of it.

Some of these concerns are more valid than others. I'm just not sure I'm in the right head space for this opportunity, and you can only do full time language training once in your career. But I'm also very resistant to change and I'm not sure how much of this is me being lazy and wanting to give up what is, usually, a pretty flexible and easy job. But on the other hand maybe that IS valid - I have two kids under four, a lot going on at home, and I'm not sure I have the mental capacity to have a lot going on at work AND a lot going on at home?

If I say no there's no guarantee that this opportunity would come up again, but I would definitely be able to take part time language training starting in February.

Help. Should I do it?