Yes. If you are a UK taxpayer, then you can have a Penfold pension. This means that you are paying income tax in the UK on your earnings. So, you don't have to be a UK citizen, and you can be living abroad you just have to make sure your income is UK-based! Please just make sure you enter your UK-based address when you fill out your personal details.
If you retire abroad, you can still contribute and withdraw your Penfold pension, at your UK marginal tax rate. When the time comes to withdraw your UK pension while living abroad, it's best to consult with a local tax advisor to know the exact tax implications of this withdrawal.