You can't search by name - they only log reports etc against URNs to protect childminder's anonymity since they are mostly individuals working from home with lots of young children around.
If you are a parent and have a childminder you want to look up ask them their URN and they should be happy to tell you, otherwise you can ring Ofsted on 08456 405060 with the persons name and location (town, village, etc) and Ofsted should be able to confirm that they are a childminder and give you the number to check their report against.
If you know their postcode then put it in as "your postcode" and they should come up first on the list. You can usually work out from the report if you have the right person as there is some basic info about the setting.
BTW please don't read too much into ofsted reports.
We've had 3 CMs and with that (admittedly small) sample there has been no relation between the ofsted grading and how good they actually are. The first "good" one was appauling, the "satisfactory" one was great and the second "good" one is wonderwoman
Also note that not all complaints show up on these reports.
TBH I would avoid reading the reports until after you have met them.
Exactly muddleduck - as a c/m myself I don't have much thought about the reports. In fact, when looking for a primary school for my daughter I won't even be reading them. Word of mouth, and meeting them would tell me a lot more than that report. When I was looking for a c/m myself it didn't occur to me to read them, I just went with a gut feeling every time.
I'm sure you're right Muddleduck.. our last childminder was fabulous, she adored our ds, was like his third grandmother. He used to run off to her every morning and collapse in to her not inconsiderable bosom He loved loved loved being there, and there's no way she would have got an outstanding on her ofsted report, her house was chaotic, tiny, she didn't do any of the things you're "supposed" to do, but all the children adored her. To them it was their second home. I would gladly pay for her to move house to be near us so she could carry on with ds if I had the money!