Well Zuzana, thank you very much for your very interesting question. The first thing I want to say is I wouldn't worry about trying to use 'shall' rather than 'will'. I can think of no social situations where using 'will' instead of 'shall' would cause social offence.

In fact, in modern English, 'shall' is rarely used in American English and only in specific situations in British English. 'Will' is the dominant form today.

So when giving information about the future and making predictions, we can use either 'shall' or 'will' with the 'I' and 'we' forms.

So we can say either, 'I shall be ready at 8 o'clock' or 'I will be ready at 8 o'clock'. In both cases the contracted form is 'I'll'.

We would normally use 'will' with 'you', 'he', 'she', 'it' and 'they'.

For example, 'Tomorrow it will be cold and foggy with light showers in the east.'

Do you understand?

Zuzana responds:
Yeah, I understand it. Thank you.

George responds:
That's great.

See also:
JustSomeLyrics
105
105.123
Junior Gong (Damian Marley) Give Dem Some Way Lyrics
Be Not Afraid John Michael Talbot Lyrics