My job also and it is incredibly hard. @Larrythelamb84 training is now fully paid up, in West Midlands anyway, and lasts 8 weeks. I've now moved onto Dispatch which is even harder, but P.A. aid the same, which is frustrating.
The shifts will not necessarily be 12 hours either. Usually earlies, lates and nights. Totally buggers up your circadian rhythm.
It is an incredibly interesting and exciting job, but you have to be very emotionally stable as one minute you will be dealing with a stolen car and the next, talking to someone for an hour trying to talk them down from a ledge or self-harming,whilst the ambulance is stuck in traffic. You won't be expected to do just 9's calls either as you will also have to do 101s and in some places, the Live Chat online.
Also at the end of the day, it is like any other call-centre job, with remembering to put your codes into the phone just for a loo break and getting long calls approved by a supervisor. It was way too strict for me and I'm much happier doing dispatch, whilst equally stressful, is a more relaxed environment, apart from when you have 3 or 4 (or more) critical incidents going off and no more resources left as the cuts have slashed everything to the bone.
It can also be entertaining if you have a look on some forces Twitter pages, for example of why not to call the 9's; such as wanting a free taxi home.
The recruitment process is incredibly long as well. I applied in the April and started in the November with loads of online assessments and complicated vetting processes.