No probs as I say pretty simple stuff. I'd say replace instead of cleaning, by all accounts cleaning is a temp fix. Don't have to go BMW, I read on a few places on the forum that Vaico are OEM or OEM quality, there's prob other brands - just don't get the £30 ebay ones.

Need to remove the radiator cover, 2 metal torx and 8 plastic screws/rivet fixings. Can remove the engine cover too, but mainly for light reasons rather than access.

Make sure you take out these little inserts too otherwise you'll lose them when removing the cover.
Fetch the fan out next

Remove this torx screw

Then use a flat head screwdriver to tease out the head of the rivet (middle bit)

Disconnect this plug, squeeze it at the cable end

...and this one, squeeze both sides. Then you can just lift the fan assembly up vertically, it sits in a guide of sorts so will come up straight.

Now you can get at the solenoids in terms or light and access for hands and tools, do one at a time to be safe.
Depress the metal clip and wiggle the connector off. Just the one bolt to undo (replace ideally, reusing is not world ending). Pop some rag underneath the solenoids and on the undertray in case of drips.
Use a gentle twisting and pulling combo to remove solenoid, you may need to retrieve the old o-ring from the block, clean the recess and surrounding area.
Refit is the reverse basically. I found locating the o-ring in the block first easier in terms of getting everything to fit properly. Grease the o-ring a little with some oil, prob not essential but something I've always done.
Once the o-ring is located in the block, insert the new solenoid with a gentle combo of twist and push. The little plate the bolt goes into should be flush with the block, this will ensure correct fitment of solenoid and that it is seated.
Then you can refit bolt, connect back up, and move on to the next one.
Once both are done, bung the fan back in and reconnect it and just start up briefly to check for initial leaks. Startup might be a bit rough initially once oil gets round the solenoids etc but will settle.
Refit everything else and go for a spin and check for leaks again.
Hope I've covered everything and that it is all clear!