But that's irrelevant, and indeed an argument that globalisation and integration with other countries is a necessity rather than an argument against them. Unless you're happy with massively decreasing our living standards.
It's a bit of a myth that countries have to be self-sustainable - North Korea tried that, and obviously utterly failed. Even without a horrible dictator at the top, the fact of the matter is that technology and growth for the last few hundred years have been reliant on trade and movement of labour, and as such we can't just say "oh, we should stop now" as though the rest of the world won't just carry on without us.
The most important point is that the end of the line for growth is not some arbitrary line in the sand that we draw, that only ends up stifling living standards and causing problems through its artificiality, but something that will naturally happen when it's impossible to continue growing. What people forget is that growth does not inherently mean 500 storey tower blocks over the whole of the UK: destroying the landscape and wildlife does eventually become bad for the economy for numerous reasons - most obviously the total destruction of agriculture. Plus things such as the Human Development Index rely on such things - that's more important than economic growth, although at the moment they're closely tied.
