Probably like the day to day life in any RA unit. I also wouldn't pin hopes on 40 being in NI for too much longer.
Day to day - equipment maintenance (reduced now, due to whole fleet management), training - individual training for promotion, training for your "trade", training for role (guns), training for deployment (maybe not in role), PT, exercises, adventure training (if you're lucky)...All on a training cycle that aims to bring an individual, then Batteries and eventually the whole regiment to a certain standard. This is separate to preparation for operations (which may be in a different role).
Day to day life sounds good, I am interested in 40 RA due to the connections with the Lowland border region also I play the bagpipes so I should be able to play with the pipe band and lastly my wife is from NI so this could work out nicely,
The blokes wont go - they'll be moved to other units, probably as formed Btys.
If you want light gun for ops reasons, every Close Support (AS90 or Lt Gun) regt does Afghan and converts to Lt gun if they're not already with it.
At the moment, 7 Para RHA (Colchester) and 29 Cdo RA (Plymouth) have Lt Gun, but are also specialist volunteer units, with extra training on top of your Gunner stuff (7 do P-Coy, 29 to All Arms Command Course - AACC). 4 Regt have Lt Gun for now.
I would just be cautious of choosing a Regiment based on where they are based this week - they may move. For recruiting area fine - you may find lots of other lads from your home area in the unit. You may not if they're in Germany, or have been. Besides that, you may find a particular unit needs you more than others and when you put down "Guns" on your trade choice, they'll send you where you're needed most, with where you want to be a close second.
On top of all this, there is a proposal to convert every Gun Regt to having 2 batteries of AS90 and of Lt Gun under new structures - this will not affect 7 & 29, but may see your AS90 Regts permanently gaining a Lt Gun Bty and "losing" an AS90 - equipment shuffle only and probably some retraining reqd.
I have put 40 Reg RA down as my first choice so fingers cross I get it, the regiment not being based in NI is no big issue for me I would be happy to be sent anywhere, I was reading that 40 Reg have just had a purpose built camp for them its a shame they might not be able to make use of it, Also how does this stand if the regiment may face the chop on the upcoming Afgan tour?