DH thinks we need a portable loo, even if going to site with toilet block. I think I managed without on throughout 18 years camping with my parents and we will manage, too.
DDs will be 4 and 7 by the time we go. 4 yo is toilet trained during day, but in pull-ups at night. 7yo has bladder like camel, but tendencies to imagine she needs the loo if she thinks of it last thing at night!
And we have a small car and have just bought a very lovely, polycotton tent in an extremely big bag . Are going to have a trailer by the time we go, but packing space could still be a bit tight.