Seemples!
Google search
blenheim n3529
third link down for AIR81 file piece reference, then TNA discovery catalogue for entry
or
once you know it's in AIR81 from Google then use TNA discovery catalogue advanced for any of the crew names or aircraft serial.
Same search in Discovery for both N3529 and N3608.
Bit more background
Normally FA (Flying Accident) are F1180 held at RAF Museum - Fatal accidents usually have P (Personnel) file reference on the front page. You can use this Air Ministry General Registry number for a "Former Reference" limited search in Discovery but not all files will be transferred.
FB (Flying Battle) did not raise F1180s so P file (also called Cas File since it was held by Casualty Dept) is the only route. Again not all files currently transferred (latest tranche is late 1940) - other tranches being prepared but you can apply direct to Air Historical Branch for details from any P file not yet transferred to the public domain.
https://www.raf.mod.uk/ahb/
Some F1180s were raised for FB losses if the cause was not clear eg intruder losses to returned aircraft over UK, aircraft damaged by enemy action that later crashed over UK etc so no hard and fast answer of F1180 or Cas/TNA AIR81 file - you need to look for both.
Ross