This is a work in progress where halfway through I realized that what I wanted to do wasn’t achievable via the Office VPN, I thought someone else might find it useful:

tell application "System Events"
tell current location of network preferences
set VPNservice to service "VPNNAME" -- name of the VPN service
if exists VPNservice then connect VPNservice
repeat until (connected of current configuration of VPNservice)
delay 1
end repeat
set isConnected to connected of current configuration of VPNservice
if isConnected then
-- Do something
end if
end tell
end tell