auld you sound like a great catch for any company, your skill set is varied and loads of experience to boot! You are ultimately employable.
Please sit down asap and "brain dump" all the facts, dates and events about your circumstance into a document (and security copy it at least in 2 separate locations. It's great you feel strong to appeal, more power to you. The critical piece is reliable consistent facts, chronologically noted. Keep it brief and to the point.
Try not to be tempted to think in terms of quantifying any payment. Focus only on creating your case for appeal. Worry about the payment later down the line.
If you have a strong case, then things will follow on positively from there.
As you know, ACAS won't give you advice, only guide you on law and process plus Employment Good Practice (to help you recognise if your employer has not been fair and reasonable).
My advice is to do as much of the heavy lifting yourself in terms of capturing the facts and creating your case, only then run it past a legal expert, so they are just looking for any gaps, anomalies or clarifications needed. It will save you ££ and it will increase your confidence to know it has been validated by an expert.
to all who have gone thru shit like this, it's horrible.