Hi Dartford Dad
It's my understanding that there is no order preference on the CAF form anymore, well at least that's what we were told last year. We put Willmington first and the Leigh second. Our daughter missed out on 11+ by 4 points but we didn't even get the leigh we were allocated Swan Valley, Aarrghhh! hence our daughter at a fab independent school now (although its a struggle financially)
The leigh is massively oversubscribed, a friends daughter who put it first and lives on their doorstep didn't get a place and no one got in on appeal! The headmaster said last year that all applicants are given a number which is randomly selected so I don't think it would matter where you put them on the form, last year was the first time this method was used.
I know you've put in form now but be prepared to think about third choice and alternatives. That said here's hoping your daughter passes11+ and as tired mum says Willmington was under subscribed so there are places for those that qualify and if not all goes to plan there's always the appeal process