I have something I really want to do this weekend, but I don't want to get half way through and then not finish it.
I have something I really want to get finished this weekend.
詳しいシチュエーションがわかりませんが、下のように言えるかと思います。
ーI have something I really want to do this weekend, but I don't want to get half way through and then not finish it.
「この週末すごくやりたいことがあるけど、やり遂げないで途中でやめたくない。」
half way through「途中で」
ーI have something I really want to get finished this weekend.
「この週末にやり遂げたいことがあるんだ。」
簡単にこのようにも言えるかと思います。
get finished「終わらせる・やり遂げる」
ご参考まで！
カナダ 
