Unless there has been a change in the legislation, there would be no problem with buying art, which would be for use wholly and exclusively for the promotion of one's business, having it treated as fixtures & fittings and writing its cost off over 8 years against Income tax.
The question you should be asking is what will be the consequence of this. Best illustrated with an example:
(Assuming you are, and remain, a high rate taxpayer):
Say you buy art at a cost of 8,000.
You display it only in a business premises, and therefore it qualifies for capital allowances.
So you deduct a 1k allowance from your profits each year for 8 years, saving you approximately 4k in income tax.
What happens when you either sell the item, or cease in business, or just put it in your sitting room? Well it is treated as a disposal of the asset, and gives rise to a balancing charge, as you have fully written the cost of the item off against your income. This balancing charge will be based on the selling price (or Market value) of the art. So if you've bought well and the item doubles in value, you get hit with 16k of extra income, or 8k of tax, in the year of disposal.
If on the other hand, you never claimed the item as a business asset, you would be liable to CGT when you dispose of it, on the gain, which in this case would be 16k - 8k. This would be a liability of 2k at current rates.
So under option one, you save tax up front, and get hit with a big bill at the end. Under option 2 you get no tax break up front, but a much smaller tax bill later on.
A separate issue worth considering here is that you propose to display the item in your home office. There could potentially be implications for the validity of PPR relief, if you start representing to Revenue that part of your house is used wholly and exclusively for business purposes...