Anyone made an 'in-year' application for a school after moving area before DC starts in reception?

[schooladviceplease2015]

Did it take long to process?

Was it a simple thing to do?

Most authorities for a place in September in reception would not count this as in-year, they will take it as a late application for September.
How long it takes to process is going to depend on the school and the LA and exactly when you make the application. Anything applied for after the end of term will definitely take longer.
If you apply to the LA then they will look to see if there are places at the school, probably be saying no places available at which point you can go on the waiting list for the school and consider appealing. If the school has places then you will be offered a place and that should only take about a week.
You do need to emphasis to the LA admission office that you have moved into the area and that you are a new application because they will assume that as you are applying for a reception place for september that you are already a resident.