Is there much point in doing a HPI check when it has already been bought a few weeks ago?
yes, because then, despite it potentially being on the register, the OP will know this for when he comes to sell it on.
its bad that he hasnt checked it already, but given the issues he has highlighted, I would personally want to know if it was my car.
OP. if it is on the register, take it as an expensive lesson learned and always HPI check any car you are potentially going to purchase.
its not the end of the world as if it has been crashed, it could have been repaired to a decent standard. but it will affect your resale value.
do you have any copy of the cars listing from the internet or advert etc?
if it isnt HPI clear, the dealership should have made this very clear to you.
edit* just seen that its hpi clear, may be worth having a specialist inspect the area around the badly fitted bumper for any repairs or impact damage because as said, a car can still be involved in incidents without it being reported on insurance database. HPI is only a guide