Use an image you feel comfortable with, the duck is fine. Its colourfull, amusing and unoffensive ( non threatening)
Maybe think of a strap line to work in conjunction with the duck.
"squeeky clean ...For a "Quacking" good service!"
"Do dirty windows ruffle your feathers?"
Tired of big window cleaning BILLS?...
Instead of listing every service you provide, maybe.....
" Extrenal Property cleaning service, specialist in PVCu cleaning and renovation."
Mobile phone no is ok, freephone number would be better( 0800)
"Go on..... give the duck a phone"
Hope this gives you something to think about...
Also with your photographic eye, getting the image balance alongside the text right should be fairly easy for you, dont let the price of the graphics stop you from creating what is in your minds eye.
And what I mean by that is, spend a bit more ( if you have to to get it spot on )
otherwise you may as well stick letters on from the local hardware store. Oh and dont let the vinyl cutter tell you he cant do this or that, he.s talking balloney, tell him "my way or highway"
Good luck
Mark.