Given notice

Possession - Section 8 and Section 21

I issued a Section 21 to my tenants as I need the property back for personal reasons.

I have given them 3 months notice instead of the statutory 2 months as they have been good tenants

The notice was given on 30th May and is due to expire on 27th August

Today , I received a request from a referencing agency asking for me to give the tenants a reference for a new rental property

I realise that they have to give me a months notice but very few tenants realise this once the landlord has given notice and I don’t want them to lose the new rental as that would cause me a hassle if they were not to find anything by the 27th August and stay put as is their right.

I didn’t think they’d find a place so fast and don’t like the idea of losing the rent so early but that is one of those things and I’m glad they have found somewhere especially as they have a dog and I was charging them £200 below market value rent

My question is , as I am sure they are going to leave before the 27th August and not give proper notice ( if any at all)
Do I need to get them to sign the NTQ?