So as I understand it, you are currently in Oman, but the house that has been bought 50% with your money but 100% in his name is in the UK. And there is some kind of intent to buy another property (but a flat) and put that into your name.
I'm going to guess that this is about stamp duty. If you own only one property in the UK then you pay stamp duty at the standard rate. If you then buy a second property, the stamp duty is doubled.
So if you buy the first property jointly, it's the first property for both of you. And when you buy the second, it's the second for both of you and the stamp duty is doubled. Actually even if it is a second property for only one of you, the stamp duty is still doubled.
But if the first property is put in his name and you don't have a property, when you come to buy the second one in your name, it is your first property and the stamp duty is at the standard rate.
How much money you might save on this scheme depends on the value of the second property as stamp duty rates are on a sliding scale.
Its a fair enough scheme, except that it should have been explained to you beforehand and you should have had legal advice to protect your interest.
Clearly insisting on putting the first property into joint names now would destroy the scheme. The value of the scheme depends on the value of the second property.
One alternative option available to you would be for your husband to give you a mortgage on the first property for the value of your investment in it. Then you aren't named on the title deeds but you have real protection in the value of the property as your mortgage can be registered at the Land Registry and the property can't be sold without you releasing the mortgage.