Brendan,
Welcome to the Forum, indeed.
Firearms deactivation is entirely the result of political decisions and statutory regulation by a government--it almost never has anything to do with safety or reliability. If you search the Forum for posts by TAC Foley and the subject "deactivation", you will find extensive information on firearms deactivation as it is practiced in the United Kingdom. If you go to
http://www.lugerforum.com/, select the Member Gallery, and go to page 10, you will find a detailed pictorial of a UK deactivated Luger.
By the online auctions I have seen, apparently the value of deactivated Lugers in the UK is respectably high, due no doubt to the fact that these are the only guns obtainable. Elsewhere--in the US, for example--deactivation reduces a Luger to the scrap value of the steel.
By all means, if you are able to obtain a working Luger, you should certainly do so. Besides, with your intent to join a pistol club, you will discover that Lugers are highly accurate and tremendously enjoyable firearms to shoot.
--Dwight