I'll get my work done as quickly as possible and go home because I'm supposed to be off today.
Since I'm supposed to be off today, I want to go home early.
ご質問の文を直訳するとだいたい以下のようになります。
I'll get my work done as quickly as possible and go home because I'm supposed to be off today.
「今日は休みのはずなのでなるべく速く仕事を終わらせて帰ります」
「～したい」はwant to ～でも表すことができますが、あえてwillを使いました。
willを使うことで、さっさと仕事を終わらせて帰るんだ、という意志を込めています。
少し長い文なので大まかの意味のまとまりごとに切ると以下のようになります。
I'll get my work done「私は仕事を終わらせるつもり」、
as quickly as possible「可能な限り速く」
and go home「そして帰宅する」
because I'm supposed to be off「なぜなら休みのはずだから」
※be supposed to～は「～のはず・～することになっている」という意味です。
today.「今日は」
二つ目にご紹介した文は
Since I'm supposed to be off today, I want to go home early.
「今日は休みのはずなので早く帰宅したいです」
という意味です。
「仕事を早く終わらせて」の部分を一気に省略したのは、「早く帰りたい」という発言の裏側には「さっさと仕事を終わらせたい」という意味も読み取ることができると考えたからです。
ちなみに、ご紹介した二つの文で、「～だから」の部分を一つ目はbecause、二つ目はsinceを用いました。
becauseは理由を極めて明確に提示する役割があり、事情を知らない相手に伝えるような場合にも適しています。
逆にsinceは既知の事柄、つまり「ご存知の通り～だから」のニュアンスを含むことが多くあり、事情を察している相手に伝える場合に向いています。
「はやく」については一つ目の文でquickly、二つ目の文ではearlyを使いました。
quicklyは動作の速さ、素早さを基本的に表します。ここでは「素早く仕事を終える」ニュアンスです。
一方のearlyは時間の早さを表します。ここでは「帰宅時間が普段働いている日の帰宅時間よりも早い」というニュアンスです。
ご参考になれば幸いです。
I'd like to finish quickly because today is supposed to be my day off.
I'm supposed to be on leave today, as soon as I've finished this I'm going back to my relaxing.
As soon as I've completed this, I'm going to continue with my day-off.
This is making the point that you are there to complete this one task and that's it! You would like to save what remains of your day-off.
"I'm going back to my relaxing" generally many people don't relax on their days-off because they have many things to do but this is not for your employer/colleagues to know.
ここでは、その仕事一つを終わらせるために職場に来ていて、終わったら、残りの休みを有効に使いたいと伝えています。
"I'm going back to my relaxing"（帰ってリラックスする）
たいていの人は休みの日でもやらないといけないことはたくさんあるのでリラックスできないでしょうが、これは上司や同僚が知るところではありません。
Today is supposed to be my rest day so I'd like to finish as soon as possible
I want to finish my work ASAP as its my day off today
I'd like to finish work quickly as it is my day off today
rest day is often referred to a day where you do not work, a day off.
ASAP - as soon as possible. often used in the English language, many people even say "ASAP" in a sentence when speaking out loud.
rest day' はしばしば仕事のない休日を指します。
ASAP = as soon as possible（できるだけ早く）
- 英語でよく使われる表現です。声に出して "ASAP" と言う人も多いです。
I'm supposed to be off today but want to get my work done quickly so I can go home early
I want to get my work done quickly so I can go home as I'm supposed to be on leave
When you are supposed to have a day off then you can say 'day off', 'holiday' or 'leave'
to do something quickly means to get it done as soon as possible as you want to do something else (you want to go home)
"Today is really supposed to be a day off, so I want to just finish my work as quickly as possible and go home
"Ideally I'd like to finish work quickly as it is my day off today and i'd like to relax at home"
If you were working whilst you were meant to be on holiday, you could say either of the following: "Today is really supposed to be a day off, so I want to just finish my work as quickly as possible and go home" or "Ideally I'd like to finish work quickly as it is my day off today and i'd like to relax at home.
本来は休日の日に仕事をしているなら、下記どちらの文も使えます。
"Today is really supposed to be a day off, so I want to just finish my work as quickly as possible and go home"
（今日は本来は休日なのでできるだけ早く仕事を終わらせて家に帰りたい）
"Ideally I'd like to finish work quickly as it is my day off today and I'd like to relax at home."
（今日は休日なので、欲を言えば早く仕事を済ませて家でくつろぎたい）
I should be off today so just want to finish and get out of here!
When working on a holiday and you want to say something like "Today is really supposed to be a day off, so I want to just finish my work as quickly as possible and go home" then the above statement is a good fit for that context.
日本 
イギリス 
アメリカ合衆国 
