I did my attic a few months ago. Fibreglass already between joists, added 200mm rockwool at 90 degrees on top of that. Try to get electrical wires above the final insulation level. You can get an attic ladder "hood" to cover the hole there. Don't block the soffit vents, you can get plastic inserts to keep the insulation from blocking them. I added a lid to the water tank and lagged over & around it, not under it so it still gets heat from below - this is all to prevent freezing now your attic will be cooler.