I have a long lunch break, but then I end up staying late at night.
I get a long lunch break, but I can't go home until later in the evening.
ーI have a long lunch break, but then I end up staying late at night.
「お昼休みが長いけど、結局夜遅くまで働くことになる」
a long lunch break で「長い昼休み」
to end up ...ing で「結局〜になる」
to stay late at night で「夜遅くまでいる」＊この場合は、夜遅くまで働いている、というニュアンスになります。
ーI get a long lunch break, but I can't go home until later in the evening.
「昼休みは長いけど、夜遅くまで帰れない」
can't go home until later in the evening で「夜遅くまで家に帰れない」＝「帰宅が遅い」
ご参考まで！
カナダ 
