Is SSaS Pension inheritance tax free and can it be drawn down before retirement age

I sadly lost my dad a couple of months ago, but I am in the lucky position where I can inherit his share of a shared SSaS pension pot. He was below 75, so I believe the pension can be distributed tax free. If I accept this money, can it be drawn down immediately, or will I have to wait until retirement age (55).
If I accept the money, does this contribute towards my lifetime allowance, or can I continue to add to my pot?