As it says on the tin, I am looking specifically for guidance for purpose built blocks of flats & conversions.  Any help greatly appreciated!

Pads are acceptable if <= 60 people are expected to use the exit AND they are familiar with the building 

 

From Building Regulations

Door fastenings
3.91 In general, doors on escape routes (whether or not the doors are fire doorsets) should be either of
the following.
a. Not fitted with a lock, latch or bolt fastenings.
b. Fitted only with simple fastenings that are all of the following

i. Easy to operate; it should be apparent how to undo the fastening.

ii. Operable from the side approached by people escaping.

iii. Operable without a key.

iv. Operable without requiring people to manipulate more than one mechanism.

Doors may be fitted with hardware to allow them to be locked when rooms are empty. If a secure door is operated by code or combination keypad, swipe or proximity card, biometric data, etc., a security mechanism override should be possible from the side approached by people escaping.

3.92 Electrically powered locks should return to the unlocked position in all of the following situations.

a. If the fire detection and alarm system operates.

b. If there is loss of power or system error.

c. If the security mechanism override is activated. Security mechanism overrides for electrically powered locks should be a Type A call point, as described in BS 7273-4. The call point should be positioned on the side approached by people escaping. If the door provides escape in either direction, a call point should be installed on both sides of the door.

 

That's as specific as it gets.

Thats great, thanks! You say from building regulations, do you have the source as I need to quote the source in this particular FRA, thanks

The Building Regulations 2010

APPROVED DOCUMENT B Fire safety

Volume 1: Dwellings 

2019 edition incorporating 2020 amendments 

I live in sheltered housing unit 

rear Exit is also an Entrance it has a push bar and a turning lock fitted  fom inside  do to lock door you turn a knob once door closed  . 
from outside you need a yale key to enter building . 
the door is a fire exit door leading to a communal garden 

my question is : I s it legally compliant with H&S and fire escape regulation  and the safety factor off security

preventing unwanted or unauthorised visitors entrance  and 

the exit off resudents and visitors in a safe manner 

You can make it as difficult as you want to get in as long as you can readily escape outwards. Having two fastenings isn't ideal as it complicates escape and renders the push bar pointless as the exit is no longer panic proof (i.e. pressure of people against the door/bar opens it without having to carry out any positive action) although the numbers expected to use the exit are likely to be under the typical benchmark where it needs to be panic proof as most sheltered housing is "stay put unless in communal space" on hearing an alarm