Depending on the force you may also need to take the CKP (certificate of knowledge of policing) which is done by the CP (Collect of Polciing) Which will set you back about 1K and only lasts for a few years if i remember.
You will need to start off as a bobby and work on the beat on 2 year probation before you can even think about applying for a specialist role.
Pay is probs minimal, don't ever expect a good salary working in the police unless you are a good rank. Eye sight will most likely be 3/36 unaided 20 20 vision aided. Like all police officer requirements. The fitness test will be very different from the officer. It will be more intense. Last time I took with the cadets was a bleep test of (I think 10) for firearms, Co1 will most likely be higher i would think. You will most likely have to apply for firearms after police probation which is very tough to get into and requires intense training to keep top notch and exams on weapon handling each year. I have never actually heard of Co1
I believe the next route will be close protection services not too sure but i would bet they would want your military/ firearms trained.