Do you have your own invoices?
I normally just modify an invoice, change it to "quote". This is the best way as already has your company logo and details there.
Then do a full breakdown of the service I will be providing, ie external window cleaning, including window frames and sills, using high reach and wash system, front glass porch to be cleaned etc etc.
Then you either have a price breakdown or a total price of work.
At the bottom you want to have something like, "insurance documents and a full risk assessment will be forwarded to you upon request".
It's pretty simple once you've done a couple.