Define "living." As a US citizen, I've gone over to the EU, including the UK, for multiple weeks to attend multiple conferences, have customer meetings, etc. I've never been anything but 100% upfront in answering any questions about the purpose and duration of my visit honestly and have never had an immigration official so much as blink at my answers.

I know that some countries (such as China) do require business visas for attending a conference and I've to get letters of introduction, etc. in order to get my visa. But it's never been an issue in Europe.