Towards the end of April, there are two dates that you might want to bring up in your English classroom. Friday, April 22nd is Earth Day. WebEnglish.se has some teaching materials on environmental issues in Teach by Calendar and more in the theme Environment 5-9.
This year marks 400 years since the death of the Bard. WebEnglish.se has a theme page on Shakespeare, mostly suitable for year 9. This page will most definitely be updated several times before the actual date, April 23rd, as more resources appear on the net.
For younger kids, there is a theme page of Spring, with materials for years 1-6, among several other Themes, before starting to plan for the End of the Year.