Capital Gains & PRR

oldbikebloke

OK lets start again
you are not married, so her and his tax positions must be considered individually

HER
She owns one property. She will be living elsewhere.
So, on paper, she potentially has two "residences" and the key question is which one will she claim is her "main" residence and thus eligible for PRR.
The answer to that is based upon the fact that where she will be physically living is as a licensee, not (important distinction) as a tenant. Therefore, she does not have a legal interest in the place where she will be living and so there is no need for her to nominate which of the residences she wishes to claim PRR on (and consequently, in the absence of a nomination - which has a 2 year time limit so she would be too late now to make it - there is also no need to apply the "matter of facts" test to establish which in reality is her day to day main home) 
.
So her status is: owner of a sole property from which she is absent (the fact it has been let is irrelevant) because she does not have a legal interest as defined in s233 in another property eligible for section 222 relief (ie: PRR)
https://www.gov.uk/hmrc-internal-manuals/capital-gains-manual/cg65047

The overarching question then is will her period of absence be a "qualifying one". For that there are 2 further conditions:
https://www.gov.uk/hmrc-internal-manuals/capital-gains-manual/cg65046

1. Did she occupy the property as main home before the period of absence? Answer: yes
2. Will she return to the property after the absence and occupy it then (or can she prove that her intent to do so has subsequently been "frustrated" by a change of circumstances). Answer: at this stage yes she intends to return

So, she has a qualifying period of absence ("for any reason") of max 3 years claim for PRR (whilst those absence conditions apply). Her position in that sense is no different to someone giving up work and going on a (<3 years) long touring holiday. 
https://www.gov.uk/hmrc-internal-manuals/capital-gains-manual/cg65066

She is not married, so cannot claim to be occupying work related accommodation as a result of her spouse's job, nor is she employed by the pub so cannot claim to have moved due to "place of work" considerations (the 4 year time limit) 
https://www.gov.uk/hmrc-internal-manuals/capital-gains-manual/cg65040

In conclusion for her CGT  the max she can claim is 3 years absence.
So using your (imprecise) dates March 2018 - February 2021 

As your intention appears to be to get married for tax purposes (I assume love is in there somewhere), I suggest you pay for professional advice on how that may (or may not) permit an extended claim if you exceed "your" 3 years. See final para which does not cover getting married for tax purposes but explains treatment of married absences:
https://www.gov.uk/hmrc-internal-manuals/capital-gains-manual/cg65068

Also bear in mind a married couple can only have one main residence, the same one for each of them. So don't claim condition b) met if he doesn't accompany you back. Divorce would also be inadvisable on tax grounds.. 

HIM
He owns one property but is now in employer provided accommodation which is exempt from income tax benefit in kind as it is "the norm" in his type of work for his employer to require him to live "on site" for the duration of that job. He is a classic example: pub/restaurant "landlord"
https://www.gov.uk/government/publications/living-accommodation-hs202-self-assessment-helpsheet

As such he has an open ended claim for PRR on his sole property for as long as he remains in that employment living in that property meeting the intention to return condition
https://www.gov.uk/hmrc-internal-manuals/capital-gains-manual/cg64555

His licensee status means he cannot sell the pub accommodation in his own name, so there is no question of him having to justify (nominate) which is his main home (the one he lives in as a fact, or the one he owns but has let) as he is not exposed to CGT on more than one property.

In conclusion for his CGT: he can claim PRR for as long as he owns only the one property, intends to return to it, and lives in that employer provided accommodation.

Julfulbub

Thank you oldbikebloke, very good of you to take the time to lay it out simplistically and all you have said more or less falls in line with the conclusions I had drawn myself. You will be pleased to here I have contacted someone today asking for professional advice, just waiting for a response. 

I hope there is love between us somewhere after 25 years together and two children. I have never wanted a big white wedding or to be the centre of attention and with outside pressure from others marriage is something I have always dodged. We have often said we should run off somewhere and do it on the quiet but that day has not come. We should take advantage of the Covid restrictions not allowing a big affair and get on with it and naturally I know that piece of paper would afford is a lot of other financial protection and less headache long term. 

As it happens I am actually an employee of the pub as I do help out when he is short and do a bit of the admin side for him. However I don’t think my role requires me to live on site for the better performance of my duties so this is a moot point.