I was in your position a few years back (ex fleet air arm)
It depends on what you fly in the Air Force, if rotary then I would suggest you do you IR down at airways in Exeter within the last 12 months in the crabs that way it counts towards your currency
If fast jet / multi engine then your hours in the last year will count towards your currency
A good way to get the hours in the last year is volunteer to fly for the Air Experience Flights on the grob.
Most airlines would expect you also to have a valid IR and MEP at the time of joining. A Multi Crew Certificate is also required which you will need to do if you fly a single pilot aircraft (eg tornado)
Hope that helps