You can get round it with luck and knowing when the US servers patch. Check the IRC channel after 4pm UK time to see if the topic states that there is no version. If this is the case, then as soon as Amadeus sorts isxeq2 out, the EU servers technically become broken until the next morning. However....
If you load your clients up around 4-6pm, they'll load with the correct DLL. As long as you don't end that client (crash, total log out etc) it tends to keep working. To be extra safe (if your computer can handle it), load some spare clients up and don't log in. As long as isxeq2 is loaded before the update (due to the US patch changes) then it will keep working until that client closes.
It's only after expansions and major game updates that this becomes a problem. Once the bugs are worked out (in eq2) they tend not to force too many client patches down the line.
There IS a patch on the US servers today at 3pm UK time. It's likely (but not certain) to have a new client build. Hopefully we can keep playing!