Firstly, commiserations on your injured beauty. I feel your pain! I guess the reference that Alan gave you is the gel coat identifier not a RAL number or colour code. If it were me, I would try a gel coat repair first. After all, if it looks bad you are no worse off, but you might be surprised at how well it blends. Problem is you don't want to buy a can of gel coat for the small dollop you need. Are you prepared to drive to Alan as I am sure he would let you have a small quantity and some catalyst.
If you get the gel coat, just brush several layers over the filled dent like paint and then finer and finer wet and dry followed by polishing compound.
If you have to go the paint route, to answer your questions - no special primer needed, just a good rub down with fine wet and dry. No special paint needed, Halfords cans or similar will be fine. If you apply several (half a dozen or so), allow it to dry thoroughly (a week or so) then cut back and polish as described before, you should get an excellent finish. A professional sprayer would cost a fair bit, but if you try the DIY options and are unhappy, that might be your last resort. If you do the prep (rubbing down) youself that will keep the cost down.
Good Luck
Greg