[bojan]

Silvering can be done at home.. you just have to fiddle with couple of very dangerous and poisonous chemicals, like cyanides etc.. I have done my first mirror in glass shop, they were also manufacturing mirrors (I had to put quite an effort to persuade them not to paint the silver coating with brown protective paint :-) But that was a long time ago, and in Europe.. It lasted for 6 months before it became too non-reflective...
It is much better to go like this to prove the concept (but, frankly, I think you are wasting your time with this) because aluminizing is not cheap process ($100 - $200 for 10" or so). You will want your mirror to came out good enough for that money, otherwise... it would have been better if you just bought it from vendors (and then it will be GLASS, 1/10 wl guaranteed)

Aluminium coating WILL NOT fill out the imperfections, guaranteed.

Perhaps, you can try to do it in couple of phases: first phase it should be just cast, to have general shape (maybe just mould the concave surface without spinning) .
Then, use this as a dish for second, thin and final coat, this time under controlled conditions (spin, temperature etc).
The third phase could be the metalisation. But you should be able to check the quality of surface before that - this is done with glass mirrors as well, even before final polishing (with wetted surface, to enhance reflectivity): Foucault test or Ronchi to determine if surface is parabolic and how much and where it departs from ideal shape.