Renting Home in Lancashire, England

Someone I know would like to rent a house they own to immediate family (Son and his sons partner) and would like to know what legislation there is regarding this.

I've had a look on Google and this site came up high and I noticed a similar thread about another area of the UK on here about it.

If it's immediate family, is there a requirement to follow the same rules as renting out to someone else?

Note that this site is primarily focused on Irish personal finance and related issues so you may not get feedback on your specific UK related queries here.

Oh right, I searched for UK only on google.co.uk

Thanks for the heads up.