Lining / insulating a concrete garage. Advice pls

Got a big concrete garage that I'd like to section off into 2 parts with the one "room" being lined and insulated to use as warm dry storage / workshop room. The other part of the garage is fine left as it is.
Anyone got any ideas of the best way to go about this. Garage is post and panel type with a pitched roof. Been thinking about attaching battens to the walls with insulation between and plasterboard but also been thinking about building a room within the garage from Thermalite blocks or the like.
TIA for any advice.
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