OP, I think you could be me!! 
Period property - tick; downsizing - tick; refurbing - tick (ongoing project tho'); money pit - tick.
When my DC have flown (checks watch), I'll be thinking about downsizing, at the moment I have a lodger to help with costs. It's worked well for me for several years. I think a kitchen could be refurbed relatively inexpensively, but it depends what it's like now and what needs doing - mine is ageing but I won't spend a lot on doing it up - perhaps painting and retiling the floor. Of course you could spend a small fortune on something fancy, but I don't think that's wise if you're leaving.
Same with the garden, fortunately mine is basically well-designed (thanks to previous owner) so won't need much to get it sorted. If you're in a large, Victorian family home, a well-tended garden is a selling point, but I don't thinking spending bundles on tarting it up is really worth it.
To a large extent, Victorian houses sell themselves - the features, space, light etc do a lot of the selling for you.
Re practicalities - it would be sensible to move to somewhere modern with it's insulation, double-glazing etc, but I doubt if I will. I'll probably find a Victorian house split into apartments where the work's been done already.