Hi Sam. This is a common problem at the moment, and Audi seems to have been affected more than any other manufacturer.
There are unlikely to be any significant changes to the vehicle as a result of WLTP, but it has to be re-homologated under the new lab tests, so its official fuel consumption and emissions figures will probably go up. That won’t affect your road tax, which is still based on the old emissions test and will be for the next 18 months or so.
There shouldn’t be any particular ‘dangers’ or ‘advantages’ with buying the six-month-old pre-WLTP version beyond the usual arguments of buying a new car vs. a nearly-new used car.