You don't need a solicitor - you can pursue it in the County Court using the Small Claims' Procedure. It will cost you, but you can do it online and is a fairly simple procedure.
Write her a letter, and head it NOTICE OF INTENDED LEGAL ACTION.
Dear.....
As you have ignored previous written and verbal requests to return my property, a xxxx, a xxx and a xxx, I have taken legal advice.
I must inform you that unless I receive these items within 28 days I shall initiate proceedings in the County Court to recover these items.
Copies of previous written requests attached.
Yours sincerely,
Keep copies of every letter, and a note of every phone cll and conversation. The court costs will not be prohibitive.