My first one - My first job/position + already doesn't work there IMO.
old, ill people- Currently the preferred PC term is older people, so I'd use that and get rid of ill as it's unnecessary if you're working in a hospital.
my summer holiday- my summer holidays
in voluntary job- use in a voluntary job or in voluntary jobs
Germany to make my Master - to taske a Master's
I would like to take up on it again,- I would like to take it up here
how charity work can be rewarding- how trewarding charity...
I experienced work- I have worked
I have been passionate about computers- I am or I have always been
This is way- This is a way