Getting a mortgage on tenants in common after partner passed away

There is a tenants in common restriction on my title with my two children being the beneficiaries via a life interest trust following the death of my husband, I want to take a mortgage out on the property (small LTV) - my husband has been removed from the title but the tenants in common restriction is still in place. What needs to be done from a legal charge perspective for the lender

Jessica - you would need to have the form A restriction cancelled 
See section 8 of our PG 6 and forms RX3/ST5 for guidance on how to apply to cancel the restriction where you have become the sole legal and beneficial owner.
From your post that may not be possible and I would recommend you seek legal advice to understand if the trust prevents removal of the restriction and/or alternative options exist as appropriate