Woah!
If it's a community hall - i.e. where public gather to do activities, etc - then it is first and foremost subject to the Regulatory Reform (Fire Safety) Order:2005, and MUST have a current valid fire risk assessment in place.
For you, this means a minimum specification will have been identified and set for any electronic fire detection (as well as for other fire measures, such as extinguishers, blankets, etc.).
Primarily, this means (and is most likely the case) that you will have a document, signed off by an expert (hopefully) who will have defined the grade and category to which the fire detection needs to comply, and to be honest, if this isn't in place, I'd throw it back at whoever asked you, and tell them to comply with the law first - that risk assessment is a LEGAL requirement.
Most likely, and without seeing the property, you'll be looking at a system which needs to comply with BS5839-1:2008. In other words, not smoke detectors in the sense of what you'd install at home. In all probability if the building is only occupied part time, and isn't attached, or posing risk to other premises, the requirement will probably be for an L2 or L3 system design.
Now, you've mentioned high domed ceilings too - those are subject to different spacing rules over the standard spacing set out - normally by reducing the distance by an amount for every so many degrees of pitch the ceiling rises. Any obstruction on the ceiling which is over 10% of the height of the room at any point will also need to be considered.
Given all this - and with all respect, it isn't something you want to "play" with - the penalties for getting it wrong hurt, and include prison if it all goes horribly wrong. Get a professional in to at least design the system (and if necessary carry out the risk assessment) - and play safe. If you're looking for a good fire company in Surrey......by the way
As Alarm Man says - collaboration is probably your best bet - get someone with experience..... to at least do the design, and commissioning....and guide you on install if necessary.