I'm working on my first project, a carbon fibre kayak seat. I have just laid down my final layer but it came out dry and doesn't have that glossy appearance.

I intend to apply a flowcoat to finish it off but not sure whether I can apply the flowcoat now to rectify the glossy appearance, or should I apply more resin to get it right first? Are there any downsides to putting the flowcoat on now? 

I'm not sure I entirely follow; wet sanding is largely used when trying to cut back and polish to a fine finish - you will need to key the surface between coats so will need to sand before the flow coat to get it to adhere but if you're looking to in turn finish the Flow Coat to a better finish (than a brush finish), then you could sand it and polish it up to a smooth, glossy surface finish.