Awarequestions

I am 65 years old and have been resident in the UK for the last 23 years. I have an Australian Superannuation scheme which I am now eligible to take lump sums or draw down. I pay tax on the income of the superannuation in Australia. I wish to know if for UK tax purposes the 25% tax free amount applies or are all withdrawals taxable here? If the 25% tax free lump sum does apply, how do I inform HMRC of this?