Re Deregistering as a HMO

HMO Licensing

I've been running a HMO since 2016 but will probably be splitting with my partner and need to repossess the HMO as my family home. Is it hard to de-register as a HMO does anyone know? If I need to sell the house I assume I need to live in the house as my family home for over two years so I'm not hit with capital gains tax. If the house has increased in value by around £200,000 it is because I've spent so much on extensions and improvements. I'm not sure if the cost of all the work would be deducted from the increase in value.

I believe I could still live in the house with two of the tenants as lodgers as understand that an HMO licence is only required if it is 3 other unrelated people renting. I assume that myself and two lodgers in that case would not require a licence. I was wondering if it was possible to rent to a family with just myself in one downstairs room sharing. This is an odd situation but has anyone heard of this happening? 

Regards Julie