What would your friend recommend?
Partly from memory you need something like the basic #105 resin / #205 hardener pack (they did some smaller "starter" packs which used to be £25 or so a few years back) but in your case I think you may well need the colloidal silica filler #406 as well, at between between about 40:1 and 10:1 mixed resin:filler ratio (the filler was about £8?). Using a filler gives improved load capacity and screw pull-out resistance as well as making a structural strength repair with good smoothness. You also use that filler when laminating making fillets and fairing-in (i.e where smooth sanded contoured surfaces are required). West also make low density and micro fibre fillers. In addition to the resin, hardener and filler you'll need measuring cups and disposable mixing sticks (these don't need to be West, where you are just oaying for their name on the cup - your local car paint supplier should be able to supply these really cheaply). One plus point of West is that once cured it can be routed, but you do seem to get a better surface with the filler
Please bear in mind that the last time I bought West stuff was pre-Covid, so prices could well be up 20 to 30% on the figures I quoted
As an aside, may I comment about routing technique? If you want a smoother bottom to your cuts tape a 1mm packer onto the top of your turret and make a first cut by plunging down slowly and then hogging away most of the material. Withdraw the router, unplunge, remove the 1mm packer and replunge to full depth, keeping the router moving as you replunge. Don't use excessive force making your plunge cuts. Hogging the waste then making a finishing cut means you can avoid those annoying cutter circles more easily