Are British expats (live in Oz) entitled to NHS when visiting UK?

[Pedestriancrossing]

Really hoping someone can point me to the answer as this is stressing me out.
My elderly PILs emigrated from UK to Australia 20 years ago. We have a family wedding coming up here in the uk and they will be coming over and staying with us for 6 weeks. Neither is in very good health and MIL has limited mobility, is no opiate painkillers and early stages of dementia.
My question is, would they be able to access NHS services (in England) for free? Or would they be charged?
Obviously neither has a GP.
I doubt they have taken out travel insurance due to cost, and are probably assuming they have free access to the aNHS (as they are British and lived in UK for many years, paid NI etc)
DHs family never talk about anything serious so the question over insurance hasn't been asked, and won't be.
Please can someone advise on what would happen if they needed hospital care while visiting?
Thank you

I can’t see that OP has described them as “expats” anywhere?

Thread title

Only in emergency, they need travel insurance just in case. Anything they need drug wise would be fully chargeable too, not nhs prescription

I used the term expat in title as a. this is what they call themselves, b. to indicate that they are British (born and lived here for 60 years, then emigrated) - the point being that they think that they're "earned" the right to NHS care when in fact nhs is a residency based service. In reality they are Australian immigrants with dual nationality between Australia and the UK.
I know many object to the term expat is based on colonialism it is still commonly used and understood.
My query re nhs care has been resolved as I now know that we have a reciprocal arrangement with Australia allowing access to most nhs care. They do have travel insurance, thankfully.
How anyone can defend the Tory government's ongoing approach to the NHS - death by a thousand cuts so that eventually any profitable services can be privatised - is beyond me.

This.
primary care an a&e emergency care is free to all.
issued would happen if had a stroke or similar or needed repatriating.
take insurance.

To add - Do check that your families medication is allowed to be brought into the UK. I mention this because it’s opioid based. If it’s allowed then they will need the doctors prescription together with the medication in the hand luggage and accessible at security. As they have dementia it might be good to check with the airline if assistance at security could be organised.

Have you read the OP’s posts?
1: There would be no charge, no matter the circumstances, as there is a reciprocal agreement.
2: They have travel insurance.

Not true at all. I work in the NHS and have seen overseas patients. We absolutely do charge them.

Most UK expats I've met in my travels and times living abroad have just faked it by keeping registered with a GP in the UK.

Depends on the Trust- where partner works it's apparently hit and miss (but lots of first and second generation immigrants and many non English speakers) and also sympathetic staff apparently .