译成英语：在英国时，你们全家为我过生日，我真的很愉快。

上面蓝莓abc 的回答很好，而朝如青丝的回答估计是那个拙劣的翻译软件搞出来的。
为我过生日，这是中文的表达方式，哪能翻译成 celebrated for my birthday 呢？（还把celebrated 写错了！）英语里面应该说，和我一起庆祝我的生日，所以，celebrated my birthday with me 是地道的表达。而且，还United Kingdom，你怎么不说 United Kingdom of Great Britain and Northern Ireland 呢！
所以，I was really happy when I was in UK, your whole family celebrated my birthday with me. 这句就挺好的。或者说：
I was really happy when your family celebrated my birthday with me when I was in UK. 我感觉，这句话更强调celebrated my birthday，强调别人为你过生日。

In the United Kingdom when your whole family celebraded for my birthday, I was really very happy.

I was really happy when I was in UK, your whole family celebrated my birthday with me.