I am afraid that you cannot force your solicitor to continue to act and be paid at the end - some firms will do this most wont I am afraid.
There are litigation loans - and you can read more here
Unless you have been ordered to do so you do not have to pay her bills.
If you are heading for a final hearing much of the work has already been done and you can use the "bundle"produced for the FDR as the basis of the bundle for the final hearing.
You can also use the existing chronology and the statement of issues as the guide to producing the up to date ones
So far as the offer is concerned if it was effective at all in terms of costs then it will only cover costs incurred after the offer was made.
All you need to do is send a simple letter suggesting a 70/30 split of the equity.
You can of you wish then say that if she does not accept then you reserve the right to ask the court to consider the issue of costs.
Many people now deal with hearings in person and there is help available on sites such as the one here
I hope that this is of assistance - please ask if you neefurther details