If I could get time off school, I'd do some volunteering
You want to go volunteering but you can't because you have school. You can explain this in one of the above ways. As you are unable to do volunteering, you can form a second conditional sentence which may be used for 'unreal' situations, and just state the reason why your desire may not be fulfilled (school): 'I would' + VERB + if + condition.
I want to volunteer but my school schedule does not allow me to!
I want to volunteer but my school schedule does not allow me to!
This sentence means that I really want to volunteer but I can't because I have to attend school and do all my school activities and homework. Some schools have a program where they allow students to volunteer as part of their school activities.
I want to volunteer but my school schedule does not allow me to!（ボランティアに行きたいけど学校があって行けない）
この文は「ボランティアに行きたいけど学校の活動や宿題があるので行けない」という意味です。
学校によっては、ボランティア活動が授業の一部になっている所もあります。
I would love to volunteer but unfortunately I have to go to school.
I want to volunteer but I still have to attend school.
Unfortunately I won't be able to volunteer because I still have to go to school.
You can use any of the expressions to let your listener know that you would like to volunteer but because you still have school, you will not be able to attend. Your listener will know and understand what you are saying to them, and if you are busy discussing certain volunteer opportunities, your listener will know that he/she can or might get you to volunteer when you are on break.
I can't volunteer because of school even though I want to.
I would love to volunteer if I didn't have to go to school.
There are a few ways you could say this sentence or change some of the words to have similar meanings:
I can't:
It's not possible for me to volunteer...
I couldn't volunteer...
It wouldn't be possible for me to volunteer...
I want to:
I would love to volunteer...
It would be cool to volunteer...
Volunteering would be nice.
But I have school...
If I didn't have school.
Because of school.
この文の言い方はいくつかあります。
I can't = できない：
It's not possible for me to volunteer...（ボランティアできない）
I couldn't volunteer...（ボランティアできない）
It wouldn't be possible for me to volunteer...（ボランティアできない）
I want to = したい：
I would love to volunteer...（ボランティアしたい）
It would be cool to volunteer...（ボランティアできたら素晴らしい）
Volunteering would be nice.（ボランティアできたら素晴らしい）
But I have school...（でも学校がある）
If I didn't have school（もし学校がなければ）
Because of school（学校があるから）
I would like to go volunteering, but I can't because I am at school.
I'd like to go volunteering, but I can't because I am at school.
I would like to go volunteering, but I can't because I am at school.
"I would like to...." means you want to do something, often used when you are unable to do it. In spoken English and informal written English it can be contracted to "I'd like...".
For example "I'd like to visit Europe more often, but the flights are very expensive".
I would like to go volunteering, but I can't because I am at school.（ボランティアに行きたいけど学校があるから行けない）
"I would like to...." は「～したい」という意味です。それができないときによく使われます。話し言葉やカジュアルな書き言葉では "I'd like..." と短縮されます。
例えば：
"I'd like to visit Europe more often, but the flights are very expensive".
（ヨーロッパにもっと行きたいんですが、飛行機がすごく高いので）
アメリカ合衆国 
イギリス 
南アフリカ 
