Conversion of private residence into three flats

[Marios]

Hello,
I bought my house over twelve years ago and I have now decided to convert it into three self contained flats.It's always been my only property and main principal residence and has never been let.
I purchased my house for £100k and the current value is around £400k. If I convert it into flats and sell them off I would probably get around £500k. I would very much appreciate it if someone can advise me as to whether I have to pay CGT or Income Tax from the proceeds of the sale?
Many thanks,
Marios

[gbarter]

Hi,
This is exactly what I plan to do, can anyone advise the position, or could Marios let me know how he got on and what the result was?

Thanks,