Company handling sexual harassment case terribly - constructive dismissal

Hello, I'm having an ongoing nightmare at work and need some help. I won't go into too much detail, but last year I was the victim of a sexual harassment/assault in the work place. Since it was reported, the company have handled it terribly. There was a formal investigation with the company lawyer, and it was advised that the attacker be terminated immediately. However, he was not fired, but allowed to resign. An email was sent wishing him well for the future. Since then, the company have not been very supportive and have done a series of things which have badly effected my mental health. I have continuosly brought these issues to the attention of management, however they have made it clear they do not care. They have tried very hard to keep what happened a secret from the rest of the company. They have not set up sexual harassment/assault processes so I feel they have not learned from this and have not taken any measures to ensure their other employees are safe. I feel as though I have no choice but to leave the company now. I want to go to an employment tribunal for constructive dismissal/mistreatment, however it seems that doing this will cost me £10-20k in legal fees. Is it possible to do it without legal representation? Is it stupid to even try this? Thank you for any help.

P.s. I have worked here for well over 2 years.