If the pub is closed down and is being turned into offices most of the beer lines will be useless, having had stale beer in them for a long time. Flojets and cellarbuoys are probably salvagable, and if there is a compressor in there it is worth its weight in gold, particularly if you have a cellar and want to run beer up from there directly - will save you a fortune on gas.
See if there are any decent brasses on the handpulls if there are any too. I manage a pub for a brewery which has just opened up another pub installing hand pumps which apparently cost £1000 each, though this is clearly well above average they are definitely worth having if you can get them. If nothing else it will make any bar you build at home pretty sweet.
Finally, breweriana. Any signs from the 60's or earlier, ideally made of enamelled metal, advertising beer, cigarettes or liquor. Aside from being awesome these are now worth a fortune on ebay.
In brewing terms you will probably find a few connectors and some decent odds and ends, but, realistically there may be little of use to you