Temp/Agency work and gold card advice

[Main spark]

Hi all, looking for abit of help/ advice, no one to really ask in person so thought i would post it up here.
im an industrial maintenance electrician soon to be redundant unfortunately, rather than jumping at the first factory I see, would rather take my time seeing whats out there and in the mean time look at temp/ agency work to see me through for a few months possibly longer if its good.
this would be whole new world to me as i have always been paye, so would I need to register self employed to be able to do this work?
also going to be applying for ecs card shortly now with my quals i believe it would be in the maintenance electrician category rather than install, will this hinder me in any way with work that i would be able to do/offered? the descriptions on the ecs website are similar but im not sure if it classed as two separate entities, the same thing just different routes to achieve?
if it matters quals are, NVQ lv3 electrical engineering maintenance, BTEC ONC electrical engineering,MPQC diploma in mining electrical operations, 18 edition, c&g High voltage operational safety course also got ipaf (3a & 3b) and confined space
thanks in advance sorry if its a bit long winded lol