Been there, seen it, done it, got the overdraft. Don't give up anything until you've done a proper business plan. A real one, not a fantasy one. Work out the absolute minimum amount you can live on (no holidays, no nights out, no Sky TV packages etc etc etc). This is how much your business needs to bring in. And unless you have some savings, it will have to start bringing it in immediately. Also work out your start up costs - premises, furnishings, kitchen equipment, insurance, advertising, stock, staff (who will need to be paid before you take any money from the business for yourselves, and regardless of your turnover). All the start up costs will have to be funded before your business starts bringing any money in (did I ask you about savings?) You could try to get a bank loan, but you'll still have to fund the repayments every month.
Do you have a catering background? Are you up-to-date with current health and hygiene regs? Do you have any knowledge of bookkeeping? (One of the big costs is accountant's fees - the more you can do yourself, the less you have to pay).
Sorry if this all sounds very negative. FWIW we are living the dream right now - and it's bloody hard work. We have a 6-figure annual turnover, no complaints - but we owe a 4-figure amount of VAT, and I spend my life chasing payments of invoices (we're currently owed £20,000). Up side - we get to work together, we can be flexible with our time up to a point, and there's a huge feeling of satisfaction that we're doing it ourselves. Down side - there's nowhere to hide when things go wrong (and they do go wrong), it's impossible for us to get a mortgage (need 2-3 years' books), we wouldn't be entitled to any unemployment benefit if the rug was pulled from under us, ditto sick pay.
I guess what I'm really trying to say is- do your homework before you take the plunge. It's a very big step, but it's not impossible, as long as you know what you're letting yourself in for.