We are planning to start with a bit of fruit and veg at 24/25 weeks like we did with DS1.
There is a lot of asthma, eczema, etc in the family, and when we started with DS1 advice was 6 months which is why we waited.
I really feel that I want to treat both boys the same as far as I can in this respect, otherwise if one has health problems then I'll always wonder if it was a choice I made.
Him having food made no difference to his sleep, that only got a bit better at 8/9 months.
Moley - I agree with Frak that porridge is weaning, so there is no difference between that and some carrot or whatever.
Weaning is like BF/FF, a massively emotive issue, and all you can do is do the research and do what you think is the right thing. I am having to bite my tongue massively at a post atm where someone is thinking of babyrice at 10 weeks....
The next thing that is this charged, I am now discovering with DS1, is where you send them to school 
Buck - the intolerances would bother me, i'll be honest. Have you talked to your GP about it? Worst case scenario for you though is 3 weeks - and if it is a sleep improvement you're hoping for you could always add a bit of formula for awhile if you are struggling to keep up with pumping etc. That doesn't help with the lactose thing though does it?