i recently forgot to take my naltrexone to work & succumbed to a lunchtime session ( a couple of beers) Can anyone advise if it is still worth taking it before drinking at night?

You likely had some nal in your system from the night before so you were probably partially covered at lunch. If you then drink later that night you should definitely take your nal 1 hour before that session. Don't worry too much about 1 slip up it would have been more of an issue if you hadn't had any nal for a couple of days and then drank with upregulated opioid receptors. I had the same thing happen to me a few months ago at lunch with no nal on hand. There are some binge drinkers like BenTSM who can go on a very dangerous bender without nal so unless you tend to be susceptible to that you won't undo your extinction in a couple of no nal sessions. This is a great time to stash nal at work, car, keychain etc. so you'll always be ready.

cheers for that reassurance - much appreciated.

Hey, I agree don't freak out. I bought a keychain pill holder off ebay and keep a supply of Nal in there for just that reason!
Very cheap to make sure it's available!
Dave