The fastest time Germany can produce the Kommandant, the German detector unit while continously building citizens, is about 5 minutes 45 seconds. This is too late if they UK player is skilled.
The most overlooked and clearly the best strategy is to wall in your HQ, berries and gold patch. There is allways enough stone for this even if the gold and the berries are on opposite sides of the HQ. How to do it as Germany:
Take the starting 3 citizens and build walls to and around the berries and gold patch. I like to do it this way because you need to finish an airtight wall by 3.30 at the latest, and 3 citizens is the only guarantee that you will finish. Build at least one tile away from the resource patches, you need space for citizens to work around it. Pump villagers, send a little more than half to berries, a little less than half to gold. of course build drop off sites since they are free. After the 3 wallbuilders are done, send them in 3 opposite directions, and each should build a gathering site next to a wood spot quite far from your HQ area and gather wood. You do this to be guaranteed enough wood for the baracks and armoury.
By now you will have frustrated commandoes outside your walls. Commandoes can't really breach walls, it takes forever, and you can just repair em from the inside. Now, if the UK player is smart he brings in an SAS guy to bomb the wall, but this will take time. Meanwhile, your far off woodcutters are chopping enough wood for a barracks and armoury. You only need 75, should be easy even if 2 of the 3 woodies die. You make the barracks+armoury, then make a kommandant and pump the great german machineguns. If I have enough wood I usually also get the free university and the really cheap physical educcation tech that makes your civilians stronger. Now you just make a gate when you need to (i.e berries run out), and you can go outside to chop wood and build granaries, protected by your Kommandant, strong citizens and a few mgs. You will be in a better position than the Rusher with his pitiful 5-8 citizens( you should have maybe twice that). If you are particulary frisky you now proceed to mg rush him.
As the USA, it should be possible to wall wood, berries and gold since they start with 250 stone. I don't play USA so I don't know, but they could do something very similar. Hope this helps, good luck.