I am probably in a position similar to yours 2 years ago: I am working and learning to code on the side.
Could I ask you how did you get the integration with xero and freeagent? I am working on an app too (vendors and orders management) and I keep wondering how to reach out potential customers.
FreeAgent and our customers have mentioned us on twitter/blogged about us sporadically over the last couple of years.
Don't just wait. We are still working on our Xero integration (I only really started on it last week), and I stuck up http://floatapp.com/xero so we could collect emails of people who wanted to try the beta, and we've got ~70 replies (mostly from accountants) by sharing it on twitter/facebook/linked in/Xero's support forums.