You still need to do an element of flight planning and risk assessment with an A2 CofC
As part of holding an A2 C of C from UAVHUB (authorised on behalf of the CAA), you still need to conduct an element of flight planning and risk assessments.
The reason for this is to make sure that you know where and how you are going to fly in your proposed area and ensure that uninvolved people don't stray into your flight path.
When operating down to 30 metres or 5 metres (in a low-speed mode) with a C2 Certified drone, you need to have a plan in place to make sure that no uninvolved people fly under your drone's operating area. The only way to do this is with a flight plan.
Remember that if you are flying in the A2 Transitional with a 'Legacy Aircraft' under 2 kg, the separation distance is 50 metres.
It is also vital that you check to make sure that you are not planning on operating with a Flight Restriction Zone (FRZ), and therefore you would need prior permission to fly within that area.
You can check if you are operating within an FRZ by checking out the UK FRZ Map: https://dronesafe.uk/restrictions/
Without doing any Flight Planning or Risk Assessments, you may find that your Public Liability Insurance is invalid.