The focus isn't really the Falklands. UK forces already use these radars, they idea is that they are easy to transport and more suitable for supporting army combat forces. 70 miles is a reasonable range for a radar when the SAM (CAMM) has a range of 25-45km and the main targets of interest are low level attack aircraft, helicopters and missiles. It's not meant for theatre air defence, that role is assigned to fighters and AWACS.
From wiki:
+ automatic hovering helicopter detection
+ artillery and mortar locating function
+ A skilled crew can deploy the radar in around 10 minutes and recover it in around 6 minutes