I am of the same opinion as daddy, if you are travelling with your EU citizen spouse and you have a valid EUFAM residence card then you do not need a visa to enter the UK.
The immigration officer might be awkward which is why you should carry with your marriage certificate and a copy of the
Directive 2004/38/EC with the relevant parts highlighted stating that you do not need a visa if travelling with your spouse.
I see you are applying for a multi-entry visa. If it is your intention to travel alone to the UK at all, then you will need a visa, unless joining your spouse over there, which you would need evidence of.
Supporting documents for a visa include a letter from your employer, evidence of family ties in Ireland, evidence of your travel plans like your hotel booking and flight tickets, bank statements from the previous 3-6 months and evidence of any savings you might have.
beloved is the enemy of freedom, and deserves to be met head-on and stamped out - Pierre Berton