I know the last time I said most of the answers were er not much good, I had a very irritated accountant tearing a strip off me - he was right and i was wrong.... but
tambos answer has holes in it - in a true joint holding - you can't leave the share to anyone else, really by definition. Someone else has given the rules of intestacy altho you say you realise you need a will.
and so having said that - you should go out and get one. I agree that a do-it-yourself will is not really for you.
Someone else has commented elsewhere that with a will - the property goes to whom you want and otherwise without a will it goes to whom the government thinks deserves it. Priddy persuasive as far as I am concerned.