Hello there.  You don't say how old you and your wife are; if you are over the retirement age then you might find this information from Age UK helpful.

www.ageuk.org.uk/.../fs25_returning_from_abroad_fcs.pdf

Whatever your age the situation is not simple (surprise surprise).  I have copied the information below from a document entitled "Heathrow Travel Care" - apparently they get a number of people enquiring when they land at Heathrow and want to know what they can expect.  The paragraph below does relate to returness from the EU.

"Access to Health Care

Any treatment and healthcare depends on the individual’s level of need. Should a returnee re-enter the UK with significant medical needs requiring urgent medical treatment, including mental health issues, they will need to present to the nearest Accident & Emergency (A&E) Department for a medical assessment. If arriving at London Heathrow Airport, the nearest Accident & Emergency is in Hillingdon Hospital. Please note that automatic access to the NHS for non-acute medical treatment is not guaranteed.
Until the returnee has become ‘habitually resident’ in the UK, the NHS will only offer free medical care for ‘urgent needs’, i.e. A&E only. Any treatment for pre-existing medical conditions may be charged for.

If a returnee intends to seek medical treatment upon return to UK, it is very useful that they have updated medical reports / assessments (in English), from their time spent overseas. They also need to ensure that they have sufficient medication for the journey, and for the interim."

I realise that these bits and pieces will not cover all your questions but hope it will serve as a starter.  I do not know the position re your wife's medication but it may be that it has to be paid for as the need will be immediate.  I am assuming you meant 2018 and not 2017 - and what with the argie bargie over splitting from the EU well anyone's guess is as good as mine!

My best wishes to you.  Annie

Many thanks for the above, yes it is 2018 that we will return, fingers crossed. We will be financially supporting ourself as we both have a 'government' pension that we have always paid tax on in the UK. It may be that we simply register at a local doctors and go from there. Thank you again.