Do the bottles you have take a screw cap or a crimp on beer bottle cap ?
If they have a screw top not sure they will hold pressure, if they take a crimped on beer bottle cap or a grolsch style levered on rubber bunged affair then they should be fine - pressure wise, although.........
500ml bottles work much better than larger bottles in my experience due to the sediment in the bottom of homebrew bottles.
With 500ml you can pour a pint in one go and leave the sediment behind. I have used 660ml bottles (bigger budweiser and cobra bottles etc) and although they work you pour a pint then the remaining beer in the bottle glugs back and disturbs the sediment, you need to pour a pint and 1/3rd in one go to avoid the sediment - decanting 750ml into a glass jug in one go would work ok.
Not the end of the world if you are starting out but 500ml bottles, or 300ml bottles work better imho,