Using UK electrical goods in Germany
In general you can use UK electrical goods in Germany with very few problems. There are a few things to consider though and one or two subtle gotchas that may catch you out.
Nominally, the voltages and frequencies are the same but in practice there are slight differences in the former. A few years ago, European countries had different nominal voltages for their domestic mains. These ranged from 210V AC to 240V AC. Now, everything works off 220V. However, when the new standard was agreed, the tolerances were widened so that nobody had to make any changes. So UK mains voltages didn't have to fall and others did not have to rise.
Any modern equipment will have no problems but some older items that were designed to work of 240V may not perform so well with lower voltage power.
The 50Hz frequency is common so there are no worries on that front.
The two areas that can give the greatest problems are baby alarms and similar devices and domestic cookers.
Anything that contains a transmitter can be a problem. Baby alarms that work with a low power radio signal are an obvious candidate. So are the sort of remote cordless headphones that can be used anywhere in a building. Different countries have authorised different frequencies for these devices and a baby alarm sold in the UK will use frequencies that are allocated to other services in Germany. The result is that, should you use a product like this you will cause interference to nearby houses and, when somebody complains, you will receive a visit from the authorities and you will be fined and have the equipment confiscated.
Cordless headphones that use infrared signals and can only be used in the same room as the transmitter are OK but clearly not suitable for baby alarms. Baby alarms that send their signals over domestic electricity wires will also not work in many German houses and apartments. The reason is that it is not unusual to find that different part of the same dwelling are powered from different mains phases and so there is no interconnection between the power outlets in different rooms.
This is the same reason why you cannot use a UK cooker in Germany. Germany uses three phase power for domestic cookers for UK single phase appliances will not work.
Don't forget to read my page about wiring and plugs for a few more useful tips on this subject.