I've just done one. Not easy at all, although I had the engine out which helped considerably!
2 challenges:
1, two of the screws for the blower cover are underneath the rear section of the airbox under the windscreen cowl. You can't remove this section with the blower in place, but you can't get directly to the blower screws with this section in place. I have a tiny ratchet which takes screwdriver bits which allows me to get to these two screws from the side instead. If you don't have such a thing then a flexible screwdriver might work. Failing that, remove the wiper mechanism and then you can detach the rear section and it will move about just enough to get a long straight screwdriver in, assuming the screws are in good condition. To remove that section with the blower in place you need to either remove the brake servo or the electronics box and aircon pipes. Utter madness.
2, in every D2 I've worked on 95% of the screws in the airbox are rusty stumps due to it sucking in our nice damp atmosphere. It takes a lot of patience to dig out the phillips-slots in the screw heads and then still many of the heads snap off when you finally get a grip on them with a screwdriver. A good pair of mole grips works for some of them, but access is difficult to most.
A brand new blower is just shy of £300, but remarkably in UK stock so available next day. I always keep a dozen of the little screws on hand so I can replace whatever does come out with new.