You’ll need to decide who will require a DBS check.
Any volunteers having contact with children / minors should be DBS Enhanced checked.
You may wish for all hosts to be DBS checked due to the vulnerability of all asylum seekers.
Your local community voluntary services organisation should be able to offer them at a discount.
Be sure to have volunteers get the online version so that they are automatically updated each year and then they will also be transferable.
If a volunteer has one from another organisation, it will not be valid unless it is the online version.
Contact your local Voluntary Action or Community & Voluntary Service organisation to verify the above.