In case you know where to go (meaning a bit familiar with the station where you make the change or at least checked station plan/photos), then probably yes. 8 min. change time is more or less usual thing. Plus in case earlier train is late and you can't catch the next train, then you can always get a stamp from conductor/station desk about delay with a train, which will allow you to take later trains.
Btw, you didn't mention the date, but we might suggest you to check also
German Railways (DB) website, London-Spezial offer from them might get you a better price, meaning you can get two discounted tickets - Austria-Germany & Germany-London. If not, then check DB website at least for the number of platforms (usually they list it in the schedule), this way you will have an idea where your next train will be in advance
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