Can I force my iOS device to connect to 1 Wifi network over another
I don't know how I managed to miss this before, but it appears they are simply joined in alphabetical order


mywifinetwork
mywifinwk2


1 Will always be picked over 2

If you are able to persuade you're IT staff to change the name (SSID) of the network then you can do this


mywifinetwork
A_mywifinetwork


or 


mywifinetwork02
mywifinetwork01


Should make sure 2 is always connected in preference to 1 when both are available

I've tested this a bit, but i'll come back and update if it stops working. So Far So Good Though.

If you can't get the SSID's changed then there is a much more complex solution here http://nootrix.com/2012/01/prioritize-wifi-on-iphone/