Hi Annabelle,
Please do take time to review the UKVI
Secure English Language Tests here.

You'll see this note at the bottom of the page:-

Settlement: If you intend to apply under the settlement route you must provide evidence that you have passed the speaking and listening components of a test at level B1 or above. You do not need to demonstrate reading and writing skills. Where a test examines all four components (speaking, listening, reading and writing) you do not need to pass the reading and writing components, you only need to evidence passing the speaking and listening components.
I've done some research for you and discovered there's an approved test centre in Preston here:-

University Of Central Lancashire
Department of Languages
Fylde Building
Preston
Lancashire PR1 2HE

Contact: EFL Co-ordinator
Phone: +44 1772 893120
Email: cvasey@uclan.ac.uk

Alternatively try here:-

Blackburn College
Feilden Street
Blackburn
Lancashire
BB2 1LH

Contact: Antoinette Jackson
Phone: +44 1254 292500
Email: info@training-people.co.uk
Website: www.blackburn.ac.uk

Let us know how you get on

Good luck