Peak Season is from March to May. Though tourists head to London pretty much all year round, late spring is when the city is at its most beautiful.
Shoulder Season is September to November welcomes the famous autumn foliage to London. Various historical festivals occur during these months, making it the perfect time to visit for a taste of London’s tradition and cultures.
Off-season: December to February are the months when the tourists start thinning out. Henceforth, the accommodation and travel costs reduce. The weather is extremely wet and chilly during this time of the year, so make sure you pack accordingly.
EU, EEA and Swiss nationals do not require a visa, and can enter London with either a valid national identity card or passport.
Nationals of 56 countries but do not require a visa for travel purpose for up to 6 months.
Nationals of Oman, Qatar and the United Arab Emirates may apply for an Electronic Visa Waiver (EVA), which is valid for tourism and study, and stay for up to 6 months.
Nationals of China and India who have a valid Irish Short-stay Visa and endorsed with "BIVS" and who have cleared immigration in Ireland can visit the UK visa-free until their current permission to enter/remain in Ireland expires.