we don't just have hot tea, we also have cold (またはiced) tea.
we don't just drink hot tea, we drink cold tea, too.
We have iced tea in addition to hot tea.
「熱いお茶だけでなく冷たいお茶もある」＝ we don't just have hot tea, we also have cold (またはiced) tea. / we don't just drink hot tea, we drink cold tea, too. / We have iced tea in addition to hot tea.
ボキャブラリー
hot tea ＝ 熱いお茶
cold/iced tea ＝ 冷たいお茶
don't just have ＝ ～だけではなく
also have ＝ ～もある
drink ＝ 飲む
in addition to ＝ ～に加えて
イギリス 
