Hi Matthew, my rate is £400 a day, I'm a tech writer. Most contract developers I know are on a lot more than that. Double mostly. They do Java/Scala/Perl. That is probably just the niche I have been in though. My very first contract wasn't particularly high £260 a day, but you get known and you can charge more once you've got people who will vouch for you.
With regards the 9 months. I write code (Python), read (a lot), watch movies, relax, listen to music. The point for me is I have to do this. Many years ago (I'm 55 now) I got very, very depressed and considered suicide. I was totally and utterly burnt out due to never ending work.
I spend quite a lot of time in Philippines and Thailand - mostly for the diving. My partner and I are keen divers (she's a nurse - but only does contract work now too). I also like photography, hiking, camping, biking and so on. I am studying for mountain leader exams.
I read Hacker News too but rarely comment. Just today and yesterday. Probably today will be the last day!
p.s. I used to work with a guy who negotiated a four day week. He is still doing that to date as far as I know. You might be able to negotiate fewer days but it's not easy.