Beanhunter we consdiered adopting from abroad but it was expensive and also in some countries there can be additional uncertainties.
Also, for us, the wait for adopting from China was so long that I would have gone out of age range by the time we got to the top of the list!
In the end, when we were ready, adopting domestically just made sense.
There are, I think, some different issues in relation to adopting from abroad. So you may wish to talk to some organisations that specialise in that, while also talking to some local authorities (in big cities, country council adoption services or voluntary agencies.
If you would like a younger child you may wish to go with country council adoption services rather than one of the voluntary agencies. However, I have heard people adopt quite young children from voluntary agencies too. Voluntary agencies find adopters for harder to place children.
Not all UK children are returned to birth parents mutliple times, nor do they all have any extensive contact with birth families. If their siblings are with the birt family there may be no contact beyond letter box. But if their siblings are also adopted there may be contact. My ds has no birth siblings (to date).