We live in a mid terrace house which is private rented the next door is end terrace, that property is bought. We fell out and they put a bolt on the street access gate but also put a chain and padlock on the gate joining the two houses .my partner has kidney failure and is blind and i thought this was a communal access gate for using to take bins out and escaping if there was a fire but i was wrong .phoned the council they couldn't do anything as its private rented and the neighbours were in bought property  so phoned anti social behaviour taskforce they couldnt do anything then citizens advice they couldnt do anything then i went to neil gray msp same crap couldnt do anything. Then the woman from the council phoned me to say if i leave bags beside my bins she would serve me notice .so i ended up taking smelly bins through the house as they couldnt get put out for 6weeks and my landlord would not get involved its all a joke its pathetic then the msp messaged me to say if i need help to get another house let him know .let down from start to finish. 

Not a fire safety issue but a property law one. There may be a clause in the freehold or leases giving a right of access making the blocking of the gate unlawful from a civil law point of view. If no such right of access exists then you are stuck, although some plaintiffs have won where the ability to access, albeit informal, has been in place for a substantial period of time.

This is one for a specialist in property law to advise on really.