Q.Dwarf lime tree
Unfortunately, whilst away on holidays, our lime tree was not watered. The leaves have all now dropped off so I was unsure whether or not I should cut the branches back.

Limes Trees are actually quite hardy and it will likely recover with care.
I would actually set the pot into a bucket of water to get the roots rehydrated. Then allow the excess water to drain off.
Wait to trim back the plant until you begin to see new growth.
Here is some links to refresh you on the care requirements.
https://www.gardeningknowhow.com/edible/fruits/lime/potted-lime-trees.htm
https://www.gardeningknowhow.com/edible/fruits/lime/lime-tree-leaf-drop-why-a-lime-tree-is-losing-leaves.htm