Do you know there is a high chance that if you remove an internal wall that your roof and ceiling will fall in? Those internal walls are commonly load bearing and hold your roof up.
It can often be great to remove or move some internal walls to open your home up and create more space but you need to engage an experienced professional.
The photo here gives you a bit of an idea, in this example you can see the large steel beams just installed in the roof cavity, beams and bracing etc.
If you need professional advise from a home renovation expert Spannenberg and Son can help.