She could have cancelled college. There was £435,000 at stake. Something she was apparently desperate to get her hands on.
She had not heard from Bamber for three days prior to their 10pm conversation. Bamber only had a short window of opportunity. So it was probably quite a spur of the moment 'now or never' decision from him.
If Bamber had asked Julie to stay with him as an alibi., would have mentioned it in her WS. He may have sussed her out, but knew she would say 'no'. Or believed she would crack if pressurised by the police.
You don't know she could have cancelled college without a really good excuse and it wouldn't have been wise to draw attention to herself at that time.
How do you know they hadn't been in touch for 3 days, can you prove it?
If she was part of the plan, why would she tell anyone JB had asked her to be his alibi? If she was part of the plan it would surely have been a joint decision that he called her when he did.
You seem determined to make JM a victim but I don't believe she was ever a victim. She wasn't a victim in that NOTW interview however much she behaved like one when being questioned by the defence.