OK, well so long as you don't marry him, you don't have too much to worry about. He could, if you split up, make a claim against your house under land law IF he can prove that he's made a significant contribution to, eg, the mortgage. If you marry him then he will potentially have a claim under family law (Matrimonial Causes Act 1973) which would put him in a stronger position. In divorce proceedings, it doesn't particularly matter whose name a property is in, the Court can make whatever order it thinks is fair.
If you go ahead and buy a house in joint names (because that's the only way you can get a mortgage), then it's absolutely essential that you make a trust deed, say 95% to you, 5% to him. That can always be replaced over time by a more evenly balanced one if you agree and if, eg, he pays half the mortgage payments.
So far as passing the property on is concerned, yes, you should make a Will. Whether you buy it together (as tenants in common would be my advice), or in your sole name, you could include in your will provision that he can continue to occupy the property either until the children have grown up, or he dies or remarries, or various other "trigger events".
I'm a family and wills lawyer and have recently started my own freelance will writing business. If you'd like more info I'm happy to give more confidential (and free) advice by email at
[email protected].
My standard charge is £75 for a single will, £130 for a couple, but if you do put the house in trust under a life interest it's a bit more complicated so the cost would be a bit (not much) more. You don't have to buy the house to make the will, it would probably be sensible to do one soon anyway so you can appoint guardians, and then as and when you buy a house, the will will automatically cover that and any other assets.