Gap year opportunities

Hello all, I applied for Computer Science at uni this year and I am thinking of taking a gap year if I get good grades in the summer since I didn't get into the unis I wanted to and so I was wondering whether there were any tips to acquiring relevant CompSci/NatSci work experience? I know about YINI and will probably apply for that soon, I saw some other good places for work experience, like IBM and Accenture, but unfortunately I decided to maybe take a gap year a few days later than their application deadline. Thanks for any help!