With regard to Tia's truancy from school and people questioning whether she may have been bullied there. I work at a large secondary school in a poor area, with a high uptake of free school dinners (the usual indicator of a deprived area) so I can only base my thoughts on my experiences. My main area of work is with Year 7 (Tia's age group), and in learning support - again an area Tia fits in.
In my experience, it is actually quite rare for children to truant due to bullying. Most school will have a good anti-bullying policy, and various staff designated to deal with this. From what I have seen, truancy often occurs with children who have problems at home. It may be due to family breakdowns/divorce; where there is a single parent and a large number of children or with families where both parents are unemployed. Sadly, the main reason the children truant, is because there isn't a responsible parent around making sure they go to school. Sometimes the parents simply don't care about the child's education, other times they may be asleep with hangovers (or simply sleep in late on school mornings as they have stayed up very late the night before as no reason to get up early) so they aren't around to ensure the children go to school. Other parents simply can't cope with bringing up their children. Children from homes like this often get drawn to other children with backgrounds similar to their own, so will truant together. They see no reason to get an education, as they don't have appropriate role models or can't see why education is relevant.
Another reason for truanting is children with Special Educational Needs struggle at school, and if they struggle too much and aren't getting the help and support they need, they will first of all misbehave to take attention away from the fact they "can't do it" and make it appear that they "won't do it". This can then lead onto the child simply refusing to go to lessons any more.
Obviously I'm not saying any of this is the case with Tia, but my opinion would be that bullying wouldn't be my first conclusion as to why she wasn't attending school regularly.