Can I ask the University or my landlord to store my possessions until I can travel to Leeds?

If you are unable to arrange removal of your possessions before the end of the contract you will need to make alternative arrangements or the University/private landlord could charge you. The University or private landlords will not have storage facilities to keep your possessions for you. You could use a packing and shipping service:   

If you need any financial support for covering the cost contact LUU Advice to see if you can apply to the Emergency Financial Assistance Fund.