My partner Sara was for many years involved with disabled adaptations to increase independence and her advice is to consider a level access shower with a seat (integral or wall hung) with a 1/2 height screen and curtain- her experience is that walk in baths have many potential problems such as getting cold while you empty and fill them not to mention leakage.
they are also very expensive. Of course if you really like baths, then you'll have to get one. Saras advice is to talk to the occupational therapist at your local council who will give free advice.
Goat