Should I add my last employer as a reference

I have been employed by the sane company for 4 years in various roles however in my last role I left before they could sack me. When applying for jobs what do I do to cover the time of my last post? I could mention I left for other reasons but then what if I don't get a reference from my previous manager? I mean she has to give a reference if requested it's more about what she says?
Please advise

It is very unwise to provide false information or to conceal information when applying for a job. If you do so and the falsehood or concealment is discovered, you are likely to be dismissed.
The previous employer can if asked provide a reference. It is obliged exercises reasonable care to be accurate in the contents of the reference.
In a situation such as yours the best course would have been to negotiate an agreed termination with a neutral reference, but you are past that point.

Well I have one last meeting with my manager. In fairness my tenure under her has not been great however what shall I say to her in order to get a satisfactory reference from her?

As you have already given notice of resignation, you have no cards to play. You could ask your manager to agree a neutral reference, but she is under no obligation to do so. If you ever face an employment problem again, take advice before you act, not afterwards.

I still have to see out my notice period which means they may still decide to take disciplinary action although I can avoid going to it as I am currently on sick leave. If they do decide to invite me to a disciplinary hearing would I still have to go especially if it is after my notice period?

You can never be compelled to do anything as an employee, but, whilst still employed, it would usually be unwise for an employee not to attend a meeting if asked to attend one.
In general, not complying with a reasonable request or instruction from an employer is a form of misconduct which may enable the employer lawfully to dismiss the employee.
Once you are no longer employed, there would be no obvious point in attending a meeting, and it is unlikely that the employer would wish you to do so.
If you were ever to find yourself in a similar situation in future, it would usually be better to negotiate an exit on agreed terms than simply to resign. But, once you have given notice to resign, if you change your mind and wish to withdraw the notice, the employer doesn't have to accept the withdrawal.
In a situation in which an employer is acting in repudiatory breach of the contract of employment, an employee may be able to resign without notice and assert what is called constructive dismissal.
It appears from your posts, however, that you may not dispute that the employer has some grounds of complaint against you.