i'm a creative professional (design) and i made the transition from employed (in a part time admin role) to self employed very slowly, cutting down on employed and taking more self employed work over a couple of years. (this was before I had a kid).
the moment i completely jacked in the employed work things really took off for me, but i had been s/e for several years in a part time capacity building up to it.
I'm a lone parent of a toddler and really lucky I've been able to work while he's been little - I've not had to take a career break and still have work and can do it around him (to an extent). I would recommend anyone doing it.
I would say maybe find a job you could do say one day a week (employed) then use the other two days to work on your business and get more clients or business being self employed. then at least you have a back up. When you're more established you can completely give up the employed role.
Sometimes it takes a while to get the business off the ground but depends on you and what you're doing. Don't get disheartened if it takes a while to take off.
There are great things to being self employed, and negatives too.
Great things: being your own boss, flexible working hours, more £ per hour, more interesting work, more experience as you do different things and more interesting projects, probably looks better on your CV if you decide to go back into work, not having to spend time working with people I can't stand (!!) - probably one of the best things about it!!
Bad things: working into the night / weekends sometimes, doing accounts, sometimes more stressful / being stuck at home a lot!!
I would say that there are potential negatives around a lack of work, but I never experience that - always have too much on. Although I have the guilt factor and never turn down work just in case next week / month is a quiet one. so I always seem to be oversubscribed!!
On another positive you'll have more time during the day to do stuff you otherwise might not, as you can spend evenings working instead. So in a way it can be a cheaper lifestyle (e.g. I can go charity shopping at leisure rather than having little time to shop at weekends). You can also offset some legitimate expenses to tax (e.g. part of your line rental, mobile phone, internet etc) if you use them for your business.
Definitely worth it and I would say go for it, just maybe have a back up plan and also more than one skills set you can outsource (e.g. I backed up mine with freelance admin for a bit which was great as a second self employed income source while the design stuff took off).
Some people just aren't meant to be part of a larger company / organisation - I spent years unhappy feeling like a dogsbody - when I went fully self employed it was a revelation and one I don't regret for a minute.
Wishing you luck :-)