Hello,
Is the word order in these sentences correct?
I went to England by plane for three weeks.
I went to England by plane for three weeks with my family.
All the best,
Kieka
Does I flew to England for three weeks. also mean that I spent three weeks on the plane?
Yes. It's the same as saying "I drove for three hours". Having said that, anyone hearing your sentence probably would not actually believe you spent three weeks on a plane. The sentence would be worse if it said "I flew for three weeks to England" but even with your word order it could be misunderstood.
You will very often hear things that could be more clearly phrased and which, if interpreted literally, could be misunderstood. In the flow of normal conversation, these pass unnoticed.
Actually, in informal conversation you don't often hear a well-formed sentence. What we actually say is something like, " Yeaah, I went ..er .. last um August it was... I think,,, yeah ...England.. flew... to England .. um... for three ... well, two and half actually...um, weeks".