I'll be in touch if there is anything I need to confirm with you.
I'll let you know if there is anything that requires further information.
ご質問ありがとうございます。
① "I'll be in touch if there is anything I need to confirm with you."=「もし何かあなたに確認しなければいけないことがあれば、連絡します。」
② "I'll let you know if there is anything that requires further information."=「もし追加情報が必要なものがあれば、あなたにお知らせします。」
ご参考に。