Disabled Bath Aids
It may be that even if you have difficulty getting in and out of the tub, you do not need a walk in bath. Perhaps you simply need a disabled bath aid to help lift you up and down.
Bath lifts are one solution but there are a number of disabled bath aids that work simply by giving you a level surface to sit on as you enter the bath and move you down and up as necessary.
These could be inflatable cubes or belts or seats that can lift and lower the occupant.
Some disabled bath aids are portable and even come with their own travel packs, letting you use a hotel or friend's bath as easily as you do your own.
If you are not sure about your balance, it may be best to install a reclining seat as your disabled bath aid and consider also whether you would benefit from having a hand rail put in.
Use Mobility Compare to browse providers and manufacturers to find disabled bath aids that could help you.