Can I leave the airport in London for a city tour? I am an Indian and will be transiting through London coming from the US, going to New Delhi. I have a nine hour stop over in London. I am a Schengen visa holder.  Will I be allowed to leave the airport to visit the city?
Is there a way to find out if I need a transit visa for a layover in the UK? Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have.
Entering the Schengen area 12 days before my visa expires I have a Vietnamese passport. I'm planning to visit Vietnam on July 7th and be back in the Czech Republic (in Schengen area) on August 29th. My visa is a multiple-entry, long-term, D type visa (for study purposes) and the expiration date is September 10th. I am afraid that the boarding officer will not allow me to enter EU since the arrival is so close to the expiration date.   Is it OK for me to enter Schengen on August 29th when I have only 12 days left until visa expiration?