You can start work without it but you'll be taxed at the higher "emergency tax" rate.
Higher tax? well let's put it this way. The correct code number will be used ...... 603L .... but the employer will initally need to use that code on a Week 1 or Month 1 basis. That means that each week or month, dependent upon how often you are paid, the tax tables will give you one-twelfth (or 1/52) of your personal allowance. However when authorised to do so by the tax office the 603L code number will be used on a cumulative basis over the rest of the tax year. Given that you will be starting to work in the UK well into the tax year .... 6 April 2008 to 5 April 2009 .... that will mean that some (or maybe all) of the tax deducted from you on the emergency basis will get refunded when the cumulative basis is first used.
Put yourself on the council tax
Well actually, look at it this way. If your husband is currently claiming the 25% single occupant discount on his Council Tax bill, he needs to write to the Council and inform them of the date you moved in. He will then lose that discount.
Things in joint names? This is now not nearly so important as previously, given the need to supply just 6 documents (rather than 20) when you come to apply for your ILR in nearly 2 years time.