And yes, epoxy is not UV stable, it will yellow in the sun. Polyester is UV stable, it should not yellow in the sun. However if you are using UV sensitive materials in the laminate (like Kevlar), then you would still need to clear coat with a coating that actually absorbs the UV radiation. Polyester may be UV stable itself, but unless it has a special additive in it then the radiation will still pass through to the laminate. This won't affect materials like carbon, but Kevlar will certainly degrade when exposed to UV. 

Not sure what you want me to say, but polyester resin is UV stable without clear coating it, and I had a quick look at the Tillett seats and they look like good products. I can't say I understand where you are coming from. 

As for links, Easy Composites stock them. Their IP2 infusion polyester is an isophthalic resin, and I believe their GP laminating polyester is an orthophthalic. Both are UV stable.