Your marriage revokes your Will but separation does not. If you separate (more of which I comment on hereafter) one of the first things you should do is to see a lawyer to change your Will. In the meantime, don’t be the first down the stairs!
Have you heard the saying (please excuse the vulgarity) “your arse is mine” well after you’re dead, from at least a trustee’s perspective that is perfectly true. In particular your trustees and executors (and not you by your Will nor your family) decide what happens to your body. The lesson here is to make sure that your trustees and executors know, and more importantly can be trusted, to follow your wishes concerning what is to happen to your remains. The usual options are cremation or burial, although I did have one old chap tell me to just shove a leg of mutton up his [bottom] and let the dogs drag [him] off into the bushes.
The Property Relationships Act overrides your Will, so if you don’t leave at least one half of your relationship property to your relationship partner(s) (the “s” here is intentional as at law there is no maximum number of relationship partners that the law can recognise you as having at any one time, all of whom qualify to be able to claim against your estate under this Act), so if instead you want to, for instance, leave more than half of your relationship assets to your children by an earlier marriage, then be aware your surviving relationship partner will have an automatic right of challenge. Note if you are mad enough to have more than one relationship partner on the go at a time, then the Court will prioritise these in order of importance to you and then give half of your relationship property to number one, half of a half to number two, half of a quarter to number three, half of an eighth to number four and so on!
Even if surviving relationship partners don’t want to challenge your Will, then sometimes Government departments will try and force them to challenge this in an effort to ensure that they get something more than they would otherwise have got under your Will and are thus put into a position to pay their own rest home subsidies.
Sometimes elderly parents become the pawns of their children (possibly of an earlier relationship) and understandings are forgotten as money hungry (step)children are suddenly closer than dermatitis to their surviving parent and become “actively engaged” in the management thereof.