Thanks both. We will try one of Pest Control that you suggested

They might be pharaoh ants - we had them a few years back. If they are, don't use ant spray - if the queen suspects her colony is under attack she makes another queen which goes elsewhere in the house so you can end up with loads of colonies. We used MR Pest Control who were brilliant.

I thought they were v rare in the UK
Rentokil or the Council Pest Control Dept

We think we have termites at our place. Any suggestion as how to check if we have them? Any suggestions for people/companies to call.

Thanks