I often visit Europe.
I guess I will have a chance to drop in UK.
We have a lot to talk to, so let's just meet somewhere and have a conversation.
Where do you live now? In London?
Since I visit Europe often, it's not difficult for me to stop by and visit UK while I'm there.
It would be lovely to catch up with you so why don't we meet up somewhere and have a chat.
Where do you live now? Are you living in London?
友人とのメールならくだけた言い方でも良いと思いますので「お話ししよう!」なら
have a chatの方が堅苦しく聞こえないと思いますよ〜。Have a conversationと云うと一般的にお話しすると云うよりは何かについて話すと云う感じに聞こえるかも。
しばらく会ってない友人と話す場合などにcatch up を使った上記のような表現で積もる話を報告し合うと云う響きが出ると思いますw