Having had to arrange a final medical for a criminal (cos thats what he is now) who had gone straight to civi prison from a civi court I can quite happily state that it does take time (don't know why it would take 5 months though, but its not like you have any pressing engagements is it? How full is your diary at the moment?)
Before the final medical (no need for a pre release) can be organised your Fmed 4 and iHR will need to be sent to a nearby medical centre (once we have agreed with them that they are prepared to travel to the prison to carry out the medical.
Arrangements with the prison have to be made too, and usually with the prison medical staff to use their facilities. This all takes time. If, for some reason, your Fmed 4 is not available then there will be delays while that is found. Long term AWOLs will have their Fmed 4 sent to APC, and if you've ever tried to get anything from them in a hurry you'll understand how fast a glacier moves.
If you went through colly then the above is all bollox and has no bearing on your case. So tell us all the information we really want to know, what did you do? How long did you get? etc