New to the site: question about driver's door lock

Hi all.

I just bought a '98 P38 diesel and love it.The driver's door handle is broken so I found another one thinking that I'd change the lock but it came with lock and (flat) keys.

Am I right in thinking the lock can't be changed over? Obviously if I do fit the new handle my existing key won't work in the new lock but presumably it won't affect the central locking from the old key even if it won't work in the ignition?

Be really grateful for any advice

you can remove the lock by taking off the houseing it sits in by drilling out or snap off the corner where the roll pin is that holds it together, then just twist it and it comes off with the barrel inside. Do the same with old one and swap over. Then drill a tiny hole in one of the other corners and fit a pin of sorts (i used a cut down small nail) and glue it in if nessassery. Sounds hard but its easy and only takes a few mins.