Hello Chris
I would use Araldite…………………beware!…………….some glues of this type give off unpleasant fumes, as the process is a chemical reaction!
I always open the window and allow the warm air from downstairs to take the fumes away and if possible leave the room for an hour.
If the part you are glueing is not under any load……………..I use PVA, give the GRP surface a good scratching first………………but then you will have to wait about four hours for the glue to harden
Regards…………………Bob