Honestly a catheter won't do you any good in the long run. You need to retrain your bladder and improve your pelvic floor muscles. A good tip I got from my physio after a 4th degree tear was:
In the morning sit on the toilet and empty your bladder and bowels if you need to. Pull up on your pelvic floor muscles and hold for as long as you can up to ten seconds. Rest for 10 seconds . Then do it again. Then rest. Once you have completed 10 exercises, stop. You should aim to do this four times per day, each after emptying your bladder. As you complete them you will notice that you will be able to hold them for longer up to the ten seconds.
I was incontinent of urine and faces after having my daughter, now I have full control again after doing this every single day. You need to commit to it, otherwise it won't work.
A catheter will only prevent you from regaining muscle and bladder control. Tena underwear and pads are amazing products that really help with incontinence. I no longer need them but they were a lifesaver when I did! Xxx