I am not sure what you mean by "semi-residential". Do you mean trading from home or that the business consists of residential lettings? also, you do not mention if you are a limited company or an unincorporated business.
if you are a limited company and you are selling the shares, you are not eligible for rollover relief as the latter is applicable to individuals and certain assets.
You may, though, be entitled to taper relief, the amount of which depends on whether a trading business or not and on the number of years the sheares owned.
If uninorporated business, the gain on the goodwill will qualify for rollover relief if you are buying goodwill or another qualifying asset.
So, on the basis of the information you gave, this is the best I can do.
http://www.tax-accounting-london.info
constantinesavva@accamail.com
We have an article on our website that gives the complete picture on the tax on sale of business - exit strategy. you are welcome to check it out.