I haven't done it myself but I know a few people who have had great results with Michelle Bridges 12 week challenges.

I go to the gym and I couldn't be without it. Have remote is your FIFO location? Is there no gym provided by the company?

My gym lets you take breaks for holidays etc and puts the time on the end of the contract. I belong to one of the chain gyms so I can often use it on holiday as well.

Couch to 5km? It's downloadable app that tells you when to run and when to walk.

A PT might be more flexible and it probably wouldn't cost more than gym memberships.

My old gym that I was at when I was at uni had 10 and 20 visit passes so you could just visit casually.
Some gyms let you do classes and/or workout on a casual basis but others charge like a wounded bull for casual visits. You could check all your local gyms to see what their membership/casual options are.