The approach would depend a little on the scenario, specifically whether you would want the dock to be editable afterwards.
In school setups where we want the dock to be fixed, we normally upload a com.apple.dock.plist file into the custom settings of a configuration profile and scope to devices.
For more sophisticated setups we use dockutil.
Like David mentioned, definitely take a look at dockutil. You'd need to deploy the dockutil file to your machines, but that's simple to do and dockutil is very powerful.
100% dockutil is the right tool for the job
but config profiles also work
check out Michael Page's site for a tool that creates a profile you can use
http://errorfreeit.com.au/blog/2015/4/28/dock-master
@m.higgins If you're forcing a dock, I second @calumhunter's suggestion.
Otherwise: dockutil.
I've an example of how I use it to add one app, here.
You can then expand that for you use case.
Ok much appreciated for the response. What about adding third party apps to the allowed apps list drop down?
Any ideas on this?
We have accounts that should only be able to open Word for example, but it is not in the drop down list