Undoubtedly wholeheartedly get liability insurance, I've personally got £5million cover, but you may not need that much. Professional indemnity insurance is another possibility, but depends on what work you intend to be undertaking.
definitely need insurance these days - even if you tread dirt into someones carpet it could cost your a fortune
Be confident in your abilities. Accept that unless you did quotes in previous jobs you're likely to make some quoting mistakes at first. Yes, definitely get liability insurance and tools insurance. I've found Yell.com brings me in a good few leads so I'd recommend it. Build a reasonable website. Be pretty strict with yourself about records/receipts/accounts (I'm not and it's always a pita when I do come to do the accounts as a result). I'd suggest trying to avoid subbying, my experience of it isn't good and I've banned myself from doing it again-the work WILL come, you don't need to panic about it and go making some other chap/chapess money off of your labours.
If your a handy man then rented property management companies will supply you with work. Contact a few. Not my sort of thing. I charge by the day plus materials when pricing. Never give verbal quotes.. Ever! Email or write to customers. Get decent business cards. Ebay. Sign written van. Done that myself off ebay again. Don't buy anything with cash as the **** receipts are a pain, all on card or account so you have paper trail. Find an accountant that will charge £250 ish. Insurance off the net as is cheapest. Get logo shirts and stuff from local company and its not much more than off the shelf stuff. You need to look the part. Good luck