You might want to consider going Ltd.
If you go Ltd, and you rent the premissis you can charge back a portion of your rent to your company through the DL account.
Also if you are just under 70k a year,.that's not bad if you are on your own, Lee Pryors guys each turn over between 60k and 70k
As far as HMRC inspections are concerned, they will argue that black is white if they feel that they are able to intimidate you enough in order to extract money from you, so it doesnt matter what you do they will interpret their rules to suit them anyway. The UK tax system is so complex now, and open to interpretation it's impossible to know what is right, and that's the way HMRC like it it gives them ultimate power.