Confidence - and how to plug those knowledge gaps on the cheap

It can be hard when you're running a small business to feel totally confident all the time because we have to be so good at so many things. In my case it covers stuff like:
marketing,
selling,
PR (my core business),
producing DVDs,
photography,
networking,
R&D - turning services into bundled products,
admin,
finance including management accounting and Ltd company regulations,
IT,
CRM (customer relationship management),
CSR (corporate social responsibility/being green),
staff recruitment, induction, training, appraisals, basic employment law & management.
design on and offline, plus interior design to create a great impression and a good working environment
There's no way that I'm expert in all these areas. After all, each are capable of supporting an entire career. So it can be pretty easy to feel inadequate. On the other hand, it's the diversity of challenges that suits my particular mindset and I expect many entrepreneurs are similar: you could say we're narrow generalists.
Even when we delegate, we still need to know enough to manage the process and cover for any lapses of others - the buck always stops here when you run a business.
The longer I'm in business, the more I try to learn, which is probably why that sixth sense that homes me in on the trouble spots works pretty well.
I soak up freebie and low cost courses and seminars (good for networking too).
Whenever a high cost course is tempting me because it has exposed a need to know more about something, I have often saved thousands of pounds with a browse through the internet and Amazon's bookshop to find sources of enough know-how to top up my expertise. Sometimes I don't even need to read the thing: it's enough to skim the contents or file the article and know it's there if I need it.
Best of all: sometimes I don't even buy it. I just add the tome to my Amazon wishlist and a few months later, the need for more info in that area has usually faded. And if it's hardened into an absolute need to know, I'm just one click away from ordering it.
But that this is no uncontrolled process. I and any staff have a individual training plans and a budget, with success outcomes to achieve - often sparked off by that initial temptation to go on an expensive course!