theres a simple switch fitted on the drivers door, under where the mirror fits if I remember. You only need the actuator/servo motor when you fit remote locking
the jack as far as I remember is same on astras of similar age, but after 91 ish the wheel bolts changed from 19mm to 17mm. heres an astra jack on the bay.... 333176942087
Slightly off topic,
I remember years ago, with the Calibre register (morning Paul & Mandy....) one went tech on the mot ramp just before billing, fella called Brian turned up at Billing in a Tigra
ive got the same problem, a bracket spotwelded for the dash has partly come away behind the clocks. its on my to do list
have an assistant with a hose outside, douse the roof +screen etc while you hunt the leak.......