hi i am a hairdresser who works mobile and also from home.

Hi Sarah

Thanks for your question

It is true that a capital gain could arise if you claim for a room in you home. However much is dependent on whether you plan to claim a proportion of the interest payments from the mortgage ( as you cannot claim the capital element)

If you chose not to claim a proportion of the interest then you can , against the heating and lighting bills claim a % of the annual costs. You have to add up all the habitable rooms in your home (excluding bathroom and kitchen) and then you claim this. So if you have 5 habitable rooms, one of which is set aside for business use, then you could claim 1/5th of those bills, (if the room is not used all the time then you then have to restrict this 1/5th claim further)

Or you can just claim £3 a week - which totals £156 a year -

If you were to claim the interest payment, then, as mentioned at the beginning of the question, then, yes capital gains would need considering. But if you were to consider 1/5th (using the room method as above for the bills) of the gain made on the sale (so sale price less purchase price) and 1/5th was less than £10,100 then you would have no capital gains to pay.
So it really is up to you - although you also have to consider whether the lenders would be happy you running a business from home, and the council could then argue that business rate apply against that room - which would be in addition to council tax.

So think it through carefully, Often it opens up a can of worms and ends up costing you more. My advise claim for the heating/lighting bills or £3 a week.

Thanks

Sam