Having done some research I see that not all resins are good to use for table/bar/desk use due to the possibility of scratching the surface. Before people suggest normal paint, I've had plenty of bad experiences with this and rubber feet of equipment stood on painted surfaces for prolonged periods of time. Additionally I'd like to have more 'depth' in the colour/design of the desk. That said I'm not planning to embed coins or other objects in the resin.

You state at the end of your post that you would like to do this work "in situ"

Using Polyester based resins WILL give you severe smell problems from the evaporating styrene -- it will be there for a long time!!!

Even though it is expensive, I would use Epoxy based resins..

The perfect one in my opinion is Wessex Resins "PermaCoat"  it is almost water clear, and very tough...  It can be used for all the layers, and can be tinted/filled to your liking.. Not cheap however ..

I have a washbasin setup and an outdoor kitchen tabletop that is done with this, and while solder-drops probably will mar the surface (No resin/paint known to me will resist the heat from solder drops, apart form the specialist "heat resistant paints" which are "high solid content, non transparent") my two very different "tabletops" are still very nice and shiny after more than a year (one of them outside constantly, but not in direct sunlight.
The "PermaCoat" shows no sign of discolouring or marking form hot tea-mugs or even cooking pots ..  But in my opinion this also often is a result of the base material being sensitive to heat. 

The EC Coating resin is almost the same, but cures harder and less flexible than the "PermaCoat"  I my opinion the slight flexibility of the PermaCoat is one reason for it being very scratch-resistant ..

Regarding post-cure to elevate the Tg of a large flat surface, I have done it with a glass plate (EeasyLease coated :-) ) and a heat blanket for motorcycle tyres -- :-)

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Thank you. Good to get a better idea how to interpret the tech sheets of these materials. Any idea where to buy PermaKote? I don't see prices listed, do Wessex Resins sell directly?