I have received a fire risk assessment report.  The report recommends installation of a Grade D LD2 automatic fire detection system, in accordance with BS 5839-6:2019, to include smoke detectors and sounders within all common escape routes, and heat detectors and sounders within the flat entrance hallways.

The building is Victorian conversion and we are all owner occupiers (2 ground floor flats and 2 flats on first floor).  Hallway is small and only one set of stairs from from front door to first floor landing.   We all have LFB installed alarms in our respective flats.  

We want to install necessary alarms in hallway as recommended in report but using the simplest system on the market.  Can anyone recommend what make to use?  

Your FRA has determined that your conversion requires a full evacuate strategy and this will require a system of mains powered smoke and heat alarms that are linked together, not single station.

If you go to here: https://www.safelincs.co.uk/radio-interlinked-smoke-alarms/ and select the Grade D2 filter in the filter options on the left you will see the range of units that are suitable. 

Radio link is simplest, otherwise all the alarms have to be cable linked.

Non interlinked or Grade F devices will not be suitable.