It’s often overlooked but, if you work from home because you don’t have other premises then you can claim an allowance for this. Even just using a corner of your kitchen table to do raise your invoices each week and check your bank (I hope you do this at least weekly!) means that you can claim £6pw.
For sole traders the amount goes up depending on the average number of hours you do each week.
Directors of a limited company can rent an office to their business. We recommend that they only do this for 5 days a week to avoid paying capital gains tax when they sell their home. The amount of rent can be set at the same level as the costs (we have a spreadsheet to help calculate this each year) so that there is no personal income tax to pay (although it should go on your tax return).