IFR C25A arrival into HHR was denied a Visual Approach by SCT Controller and given a singular option of canceling IFR to avoid lengthy delay/s; claiming an unsafe condition caused by the lack of ATC assistance.

Narrative

While on an IFR flight plan to HHR; the Controller advised that 'you would need to hold an hour go get into HHR'. I asked for the Visual Approach as I know Simultaneous Visual Approaches into HHR as with IFR in to LAX are routine. I asked the Controller for a Visual Approach clearance; the Controller refused the Visual Approach and stated that the only way I can get into HHR is if you cancel IFR and continue VFR. I canceled IFR; after which the Controller stated 'Stay Clear of Class B Airspace;' because I did not want to fly head down while looking at charts; I asked the Controller to verify the bottom of Class B was at 5;000 FT all the way from present position to HHR; the Controller stated that there is a 4;000 FT bottom one statute mile ahead. I quickly descended to 3;700; than set up WELLZ final approach fix at 2;500; this was the only way I knew how to stay at a safe altitude. I descended to arrive at WELLZ at 2;500 and than descended to HHR at a 3.5 degree angle; the VASI at HHR is 3.5 degree. I don't think I entered Class B; and was not advised as to such; but the refusal of the Controller to let us continue the Visual Approach under IFR flight plan; and the quick change to VFR; caused an unsafe situation; that caused very high workload in a single pilot jet operation. Operating VFR in congested airspace; I asked the Controller to advise me of the bottom of Class B so I could stay 'heads up' and looking for traffic and not heads down looking at charts; the Controller advised me of the 4;000 bottom and not the 2;500 bottom in the vicinity of WELLZ. I may have entered the 2;500 segment on the decent to WELLZ but do not know if I did or not. The heavy workload brought on by the refusal of the Controller of providing Class B clearance brought on an unsafe situation.