If you're going to the beach, why not take a book in English? Depending on your level, you could choose a book from the Penguin Readers selection, or a novel about whatever you like! Remember that most libraries also have an English language section, so you can borrow books rather than buying them. You could also buy a magazine or newspaper in English. When you're reading, remember that you don't need to understand every single word. If you don't understand a particular piece of vocabulary, it's often possible to guess the meaning from the context. Think about whether the new word is a verb, noun, adjective or adverb, and the clues that the words before and after the unknown word give you.
To practise listening in English, you could go to the cinema, watch a series or videos on the BBC website or TED. The latter has lots of videos about all different kinds of topics, of varying length.
If you want to work on your speaking, how about finding a conversation partner? This is somebody who wants to learn your language, and you speak for half the time in English and half the time in your language. I find this, along with my personal teacher, very helpful for my Spanish!
Writing is also something you can work on alone. Write a letter to a friend, work on your CV, make up a story, write an article, report, review, cover letter... There are lots of possibilities!
If you want to work on your grammar, think about buying a grammar book such as English Grammar in Use. Different grammar points are explained clearly and there are exercises as well as an answer key. Cambridge University Press also publish pronunciation and vocabulary books - have a look here.
I'll be on holiday in August but will be back in September with more blog posts! Have a great summer everyone :)