Bit of negativity here, don't look at the doom and gloom side of things.
There are a few options available to you:
1. Operate as a sole trader, treat your partner as an employee. You can take advantage this way of the tax threshold and increase his wages as you get nearer to the 40% band this way you avoid paying more tax.
2 Set up as a limited company, once you earn over £60,000 per annum then it is absolutely necessary to register for vat. It is a good idea to do this in the first year as this is when you'll make the most purchases i.e Van, computers, office furniture, accounts software, equipment etc. You can then claim the vat back.
Some will argue you will also have to charge Vat on your prices and it will make you less competitive, but if youre aiming at the commercial market, bear in mind they are vat registered and so claim all the vat they pay out back.
As a limited company, you take a wage out of the company each month, one for you, one for your partner.
If you require more money, you take it out as a directors dividend, this is taxed at a lower rate than your wage thus you pay less tax.
This is a brief explanation and a good accountant will give you proper guidance.
Mrs P is an accountant and in her practice going limited is being pushed as the best way to pay less tax.