I just used the parent rooms one and if full, a big one while holding her. DD trained really fast though - I can count on one hand the amount of accidents we had while she was training though and she was happy to sit on a loo but I know some kids prefer a potty. If she is happy to sit on a loo I wouldn't worry about buying something yet - maybe see how she goes. I have had to take Iz to the grossest toilets though at the local shops Now I ask her to wait because it's "stinky and horrid and can she please wait" and she holds on!
I am now looking at DS who is saying wee wee and pot when Iz goes. My CC has already started putting him on the toilet without me asking so I think you will find they are very helpful with it all. Good luck hun! Exciting times!