New answers tagged shipping
I have no experience between US/UK, but in general I am quite happy with sending packages through shipping. Where with airlines weight is key, in shipping it is volume. Most shipping is done through containers. This is both a +1 and a -1. Positive is that you don't have to bother about a kg more or less, as long as it fits the volume you are more or less ...
Almost certainly the cheapest and easiest option is to just take it all with you on the plane. For example, on Qantas each you can take two bags up to 23 kg each for free, which means that with two passengers, the total cost for four bags with up to 92 kg of stuff is zero. If that's not enough, additional bags for flights to/from the US cost A$123 ...
I experienced that shipping from Germany to other European countries is reasonably cheap (for example to Spain: 29€ for up to 25 kg with Hermes; 40€ for about 32 kg with DHL). The other way around options may be harder to find. I couldn't find any cheap carrier from Spain. However, Portugal > Germany is cheap with Chronopost (27€ for about 30 kg).
When I moved from Germany to Italy, I sent a parcel with household items using https://gls-group.eu/. Their prices were reasonable (around 20-25E for a parcel up to 40kg).
Top 50 recent answers are included