Setting up on my own

I've been thinking quite a lot recently about quitting my job in a Chartered Accountants and setting up myself in business.  My job is slow and not at all challenging and I've been getting increasingly lazy.

I have already written advertising letters and have a business card design ready.  In addition to this, I have costed the relevant software and I have enough savings in case I don't earn enough for a while.

The main concern I have is that I'm still only part ACCA qualified.  I will continue and can afford to pay for the relevant books/courses/exams etc myself.

I want to offer more than just accountancy/bookkeeping/payroll etc, but business advice too (Which my current employer doesn't).

My question is, have others done this and how have they fared?  Would they recommend it?

Also, for any who have done this, what was the response from your employer knowing you would be in competition?

I'm 24, and have 4 years of practice experience where I complete a job start to finish.  I'm fairly confident, but not an excessive risk taker!

Thanks in advance.