Thank you for your question and patience, I’m Tom and I’ll try to help you.
You can check by downloading a copy of the register for the property from the Land Registry by paying a £4.00 fee:-
Look at the proprietorship register of the title you have downloaded from the Land Registry (where the proprietors of the property are listed). If the following entry is immediately below the named registered proprietors then the interests are held as tenants in common:-
" No disposition by a sole proprietor of the registered estate (except a trust corporation) under which capital money arises is to be registered unless authorised by an order of the Court"
If there is no such entry then the property is held as joint tenants.
My goal is to provide you with a good service. If you feel you have received anything less, please reply back as I am happy to address follow-up issues specifically relating to your question.