There are bus stops right outside the pub. The number 21 bus. Here it is on Google streetview.
Google Maps
The last buses in either direction run at about 6pm towards Crawley, and 6.45pm towards Epsom.
She could have changed her clothes in that time, if she'd planned ahead, which I think she did. She wasn't wearing a coat because she didn't need one in the library, or in taxis. But later on she would need one if she planned to depart and stay dry and warm in the evening. Did her ex-boyfriend's mother perhaps give her a coat that weekend, when she gave her some old clothes?
I think she wouldn't have spent money on taxis and flowers if she was running away, unless she knew she had a means of earning money (a new job - had opened a new bank account?) or someone had offered to provide shelter/help her. She could have taken cash in hand jobs like nannying.
I also think she planned this as a sort of 'you didn't tell me what happened to my mum, so I'll leave you not knowing what happens to me'. I think the tablets and booze were staged, because you don't need more than one means - overdose and jumping off the edge of a quarry, so it looks over-staged to me.
She could have got married by now.
I do wonder what made her look into her mother's cause of death. If something didn't add up for her, there was a reason it didn't.
JMO