Your business year end, not 5 April, is relevant for capital allowances purposes. If however you are running a business and making up accounts to 31 March or 5 April, you should consider buying plant and machinery to take advantage of the Annual Investment Allowance...
One of the other capital allowance changes announced in the Autumn Budget was the reduction of the writing down allowance on assets in the special rate pool from 8% to just 6% per annum reducing balance from April 2019. The assets included in this pool include...