We'd counsel against the creation of a separate auditing function for the House of Commons. We think the Auditor General can do a good enough job.
We also favour total proactive disclosure on financial transactions and letting your constituents be the auditors. We take kind of a Libertarian approach, that members should be allowed to spend whatever portion of their budgets they choose on whatever they choose, as they deem fit, provided that every transaction is documented for the examination of their constituents.