TLDR; To answer your question "who knows what I will get". The answer is simple. "You already do, 44,000".
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How was it financed if not PCP ? (The remaining choices being a personal loan or some form of secured loan). Either of these will have a settlement figure of 44,000 less 10,000 less your payments and plus interest
You said you had gap insurance - and that it was return to invoice and it was 44,000 you paid.
The current offer (reasonable or otherwise) is 33,500. The gap payment will be 10,500. So you will receive 44,000 (ie the original RTI gap agreed value).
If you negotiate your settlement to say 36,000 you will receive 36,000 and a gap payment of 8,000. Still 44,000.
In effect, if you have bought RTI gap that gives you an agreed insurance value.
Now, if your finance is simply a personal loan it's all fine. The loan just continues as before, you go find something to 44k and buy it with the combined settlement from Swift and GapCo remembering your insurance costs will increase (irrespective of whether your NCD was protected and a 35k odd fault claim is going to impact your base premium).
If your finance is a secured loan that will need to be paid off. The balance will be returned to you.
Without knowing the terms of the loan I cannot estimate that.
Ultimately you should be able to spend 44k on a replacement and end up with a loan on the same remaining terms as what you currently have.