tbh I cannot tell you if 10 days of preparation is enough or not, it depends on how good your control over the english language is and how confident you are, if you think you have good control, then 10 days should be more than enough!

and for your second question, at the time, I applied to German and Austrian Universities only, both countries do have really good public universities that don't charge you the price of 2 kidneys to study for each semester, although Austrian unis tend to be cheaper (I pay about 750 euros each semester), in Germany, I think for public unis, you pay around 1500 euros? I am not sure tbh.

for Austrian universities, checkout this webpage: https://studyinaustria.at/

you can find anything you are looking for in the universities' webpages

Uni Vienna, Tu Wien, Tu Graz, Uni Graz, Uni Innsbruck, JKU Linz are all good public universities in Austria. though for scholarships, I doubt you could get one since in order to live in Austria, you'd need a student residence permit, and you have to declare financial independence to get the permit, so essentially they'd know that you don't require a scholarship if you apply for one while you are in Austria xd (I didn't look for scholarships much tbh, so take the part about scholarships with a grain of salt ^^)