"I think most people manage it pretty well without accountants and things are never as complex as people make them seem."
Depends what you mean by "manage it pretty well" - file a tax return that is accepted on time maybe, pay no more tax than is necessary probably not. If MrsJimmyChoo pays tax at 20% (and Class 4 NI at 9%), her version of the calculation ends up with her paying £170 more than she should be!
MrA- you really confused me putting 60/63 because to me that looked like a fraction.
Xenia- I thought the whole point ( correct me MrA if worng) of saying that any room was used for other things apart from the business was the way to avoid capital gains? It's only if a room is used exclusively for a business that you could be liable.
And another question- how would anyone know if you wre working from home- even sticking stamps on envelopes in a tiny room for that purpose?