The form "I'll be closing the order book" emphasizes that this is a future event, as the form " I'm closing the order book f" does not.

Also "as we will go into the weekend" seems odd or unnatural to me. I would suggest one of:

• as the weekend starts
• as we are starting the weekend
• as the weekend begins
• for the coming wqeekend

But the form "we will go" just does not seem to fit this context.

The form "I'll be closing the order book" emphasizes that this is a future event, as the form " I'm closing the order book" does not.

Also "as we will go into the weekend" seems odd or unnatural to me. I would suggest one of:

• as the weekend starts
• as we are starting the weekend
• as the weekend begins
• for the coming wqeekend

But the form "we will go" just does not seem to fit this context.