I am planning to visit Tenerife, Canary Islands, Spain in October from Mumbai, India. I have already applied for a Spanish visa and am expecting to get it in two to three weeks.   I have booked a British Airways ticket. I will arrive at London Heathrow Airport, and my connection flight to Tenerife is from London Gatwick Airport. In-between there is a layover of seven hours. Therefore, will I need a transit visa for going to London Gatwick Airport from London Heathrow Airport?  If it is required, can I get it on arrival to London, or do I need to apply before starting the journey?  Further information:  I am an Indian citizen and I will have Spain Business visa for three weeks before starting the journey. This is my second visit to Spain.
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.
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