I have the cupboard prepared for just that having got the plumber to fit a couple of tails to provide hot water for a rad. Have been waiting 4 years now for him to remember to dump off a removed 2nd hand rad of a suitable size, I do keep my eyes open in skips when I can remember. But now inevitably said cupboard is filled with sundry other stuff!As you no longer have a hot water tank it might be worth doing what I did. My airing cupboard is in the bathroom and I fitted a towel radiator in the back of my airing cupboard, I also fitted an electric heating element into this towel rail and the main one for the bathroom and powered them via a two hour run-back timer. This gives me back the airing cupboard and it can be used when the heating is otherwise turned off!