I'm preparing thoroughly for my trip so that I don't forget anything.
I'm preparing everything carefully in advance so that I don't forget anything for the trip.
「忘れ物をしないように入念に旅の準備をしています」＝ I'm preparing thoroughly for my trip so that I don't forget anything. / I'm preparing everything carefully in advance so that I don't forget anything for the trip.
ボキャブラリー
prepare ＝ 準備する、用意する
thoroughly, carefully ＝ 入念に
for my trip ＝ 旅行のために
so that I don't forget anything ＝ 忘れ物をしないように
in advance ＝ 先に、～の前に
イギリス 
