Maybe it's best to try short ride on side, residential streets with someone else while in a foreign country. You underestimate yourself wynrider.
I'm not sure what it is like riding on the left vs. right in UK since I've never cycled there.
Admittedly all the foreign country bike touring with our belongings in Germany, France, Czech Republic and Denmark has been with dearie... I put my fear really more on being less geospatially comfortable in unknown areas compared to him. Nothing to do with foreign country....
To me, it makes a difference to have lived and biked in big North American cities with very busy downtown areas and cyclists..which has helped me when we tour in foreign big cities. Meaning over 1 million people.