I imagine you will find it quite frustrating. Your "peers" will be 17-19 year old lads and a few slightly older guys. The young lads will be interested in having sex for the first time, looking at buying their first R reg Corsa (when they pass their driving test), downloading "bebo" on their mobile phones using some kind of electrical trickery I can't understand, wondering why they wee themselves when they have drunk beer and having to work hard for the first time in their lives.
Your interests are likely to be gardening, restoring antique motorcycles and how young policemen look these days.
To put it in perspective - some of them will be too young to drink legally.
The people with the same interests and outlook on life will be the training team but you will have to maintain your distance from them and let your work ethic, common sense and maturity mark you out as a good bloke.
Once they realise you are a good bloke, and not some unhinged loon who failed to succeed in civvy street and is escaping to the army then you will probably be given more responsibility and slack than some of the young turds who litter training regiments.
The lack of personal freedom will be difficult as your civvy life of endless weekends, taking sickies when you want and running round in the woods naked off your tits on mushrooms are well and truly over. How will you feel if wifey is crying at home and you can't go and see her that weekend because you have room inspections or an exercise to prepare for? Treat Ph1 and Ph 2 training as you would time spent in a bolivian prison. Expect nothing, don't assume you will have any time off and make sure wifey is briefed not to see you for 3 months - although she will.
Make sure you don't start training with your finances in crap order as your pay will doubtless be wrong when it starts, if it starts at all. 3 months worth of mortgage payments in the bank when you start will mean you have nothing to worry about.
Work on your flexibility and endurance - those little whipper snappers in your troop will be fast off the mark but have no experience of how hard they can push themselves - hence the tortoise will always beat the hare. You will need to do more PT before hand as your natural level of fitness will have dropped significantly since you were 18. If you can run 1.5miles in 9 min 30 sec you are doing alright. Ensure your upper body strength is good as well - 60 press ups and 60 sit ups will see you ok during training.
I would say enjoy it, but you probably won't - except some elements of the B3 course. The light at the end of the tunnel is speedy promotion (if you aren't a mong) and a seat at God's right hand on judgement day as a member of the Corps. Hurrah.
It's better than being a civvy. Well I suppose it is, but I don't know any civvies except my girlfriend, and she doesn't count.