19th (tbc): The Hoppings - Europe's largest funfair with roots going back to 1721 on 40 acres in the heart of the city of Newcastle upon Tyne, continuing to the end of June/beginning of July. As a student this was the perfect antidote to the stress of exams!
20th: National Winking Day - Can you wink? I can, but only with my right eye ;)
21st: Summer Solstice. A time when the druids and other assorted folk stay up all night - well it is the shortest one - and celebrate the dawn of the longest day at Stonehenge.
24th - Midsummer's Day aka St John's Day. I've always struggled with this one as summer's only just got going in my view. Have a look here for more information on the the traditions associated with this day and also the entire month.