The child protection issues are very worrying. Make an appointment with the DSL to say that you belatedly found out something critical and only avoided a serious breach by luck.
Email your mentor to ask when meetings will take place. It is still only week 2, but you do need your first formal meeting by the end of next week. Weekly meetings are ideal, but fortnightly is not unusual. Given you feel you have missed some key information already though, you are right to aim for weekly to start with at least.
HT if you don’t get a satisfactory response. Appropriate Body (the LA or teaching school you are registered with) if the HT doesn’t take it seriously and sort things out. You should NOT be a subject lead for anything. Remind the HT that NQTs are not expected to take on any additional responsibilities.
By the end of this month you should have a regular mentor meeting schedule, have discussed specific training needs (eg if school uses a phonics scheme that’s new to you) have seen DSL and SENDCo, know when your first observation will be and know who to go to for help for different things or when your mentor is not available. If your phase leader can’t help with assessment, a meeting with assessment lead.
If the bubble arrangements mean you can’t be observed or observe others in class, ask about outdoor lessons or using video. You need feedback and you need to see good practice in your new school.
It’s possible your mentor is overwhelmed by being back in school with all the negative media coverage about the rate of spread and testing etc, but you are right to not want time to run away with no action.