I attended one of those Fas, start your own courses a couple of years ago and found it a big help.
I think the main thing for you is to sit down and think about what you want from a business. Do you want the money, the challenge or oppertunity to be your own boss?
Running your own business can be a lot of fun (and a lot of hard work), but you need to think it through and have a clear exit plan.
If I had 300k to invest, I think I'd rather invest it in a couple of small start-ups instead of starting from scratch with my own business.