Hello,

My mom and I are planning on going to Ireland, Northern Ireland, Britain, and Scotland. We would like to just rent a car and drive everywhere. Is this possible?

Of course it is possible. However, whether it is going to be within your time and budget constraints is a completely different matter.

Greg is correct.

Look at the T&Cs to see if you can take the rental onto ferries. If not divide the trip up.

yes - of course you can drive everywhere [though you'll need to take car ferries if you want to keep the same car or to fly and get a new car to get between Britain and Ireland]

a trip like this, if you wanted to see a reasonable amount of each country and not to need another holiday at the end of it, would need 6-8 weeks minimum, unless you've been before.

>>Is this possible?<<

Well, impossible to say w/o knowing how long you have and how much of the four countries you want to cover . . .