take a look at Quickfile. As quotes need to be turned into bills and those need to be tracked and, then you want to know what you are spending - So really what you need is a system to do your books. easily, quickly and cheaply. Customers can pay on line with the stripe or paypal integration - or even set up a direct debit with go-0cardless.
I have used this system for about 6 years and seen it grow. Support is superb, its free for a low number of transactions then about £40/year. No affiliation !