This is why my late Mum didn't marry her partner. She went to a solicitor to talk this through and they said, "if you want to keep control of your money, don't get married".
Here's the thing. You can make a will "in contemplation of marriage" (the solicitor will know the proper wording) before you get married, leaving everything to your daughter.
But...
Your lovely DH could then get a bang on the head, have a sudden change of personality, and get a chunk in the resulting divorce. Or, make a claim against your estate for provision after you die.
If you marry without such a will and don't make one after, he gets your stuff on death and the first 300,000 or so of the money, house etc (and if he doesn't want to give your daughter her due, she'll have to sue).
If you don't marry, but then need care, the house might have to be sold sooner or later for care fees and it might end up in a battle between him wanting to stay in his own home and the LA wanting to sell the house now to get the care paid for.
It's a delicate situation because you are already engaged (which has social and emotional weight even if it has little legal consequence).
I'd say go and see a good STEP solicitor, on your own, ideally without mentioning it to daughter or fiancé first so you can think clearly about what YOU want.
The lawyer should be able to talk you through all the many, many potential scenarios (death, divorce, incapacity, going into care, and more) and come up with a solution that is, at least, close to what you want to achieve in those situations.
Remember you could, theoretically, fall out with your daughter as well as your chap...
My Mum left her partner a lifetime right to reside in her house as long as he didn't remarry, cohabit, or move out, and made him responsible for the upkeep. But that could still have been sticky if we didn't get on or he had taken the piss.
Another thing to discuss is who has PoA. You might need your finances or care managed before you die, so nail that down too.
IANAL but I was "the daughter".