As has already been said: get movies or books you know already in the swedish translation.
For movies, subtitles can be a great help. Also, listening to swedish music will help your ear a bit.
Instead of practising with swedish friends, look online for a tandem partner (you need a webcam, a microfone and good internet access for this). Tandem works that you partner two different native speakers who want to each learn the other’s language, and switch after 30 min. So the first half hour, both of you talk Swedish, then you both talk english.
Look for some swedish-language message boards and discussion forums on a topic that interests you, and start typing. (You know how on this board, nobody minds mistakes that non-native speakers make? Remember this).
Browse through the swedish wikipedia, and compare to the english articles (beware, though: these are not 1:1 translations, but seperate articles!)
As for children’s books, I have the problem that the simple ones are a bit too boring for adults to read (See spot run. Run spot run doesn’t have a lot of plot), while the more interesting ones (a translated Harry Potter e.g.) already have a lot of vocabulary and longer sentences. (Do Americans know Astrid Lindgren? Surely that would be a wonderful bonus to read in the original language, not only the innocent ones like Pippi longstoking or the childhood memories, but also the later ones - Mio, Brothers Lionheart, Ronja Robbersdaughter etc.)
Try Asterix comics, they have been translated in many languages.
I know that there are two line of publishing in my country for language learners: one are bi-linguagl books, the original on one side, a translation on the other side. The others are simplified - an original Sherlock Holmes story or similar, with a vocabulary of only 900/ 1200 words (plus extra words with footnotes and illustrations), or new: a mixture of English and German. Don’t know if the market for Swedish/ English learners is big enough, but your teacher might know.
Do you have a child/ pet/ teddy bear? Talk to them in Swedish about the housework or whatever else you are doing right now, alone at home, so you get used to using swedish.
Get recipes for original swedish food from the internet and try to cook that (if you can get the ingredients).
Look at google streetmap and get a map of the city you’re going to stay in for your summer course, and practise asking how to get from … to… - the usual tourist stuff, but also what you personally would ask a native (where’s the next internet cafe? Do you know Doper X, he’s from Sweden? :))
I know it’s a bit difficult to overcome the “I’m making a fool of myself/ nobody can understand me” inner voice - but speak and write online as much as you can.
Here’san essay on learning languages - scroll to the end for the How-to section.