I bought a plant from ikea a few years ago, but I have no idea what it is.

If it is what I suspect I want to use it for my cooking, but don't want to risk it.

I took it my garden centre but the spotty 16 yr old didn't have a clue!

It is potted inside, lived on my kitchen window sill, needs loads of water, constantly dies and I bring it back to llife.

Its smell is really intense if you touch it... Lemons! Okay,so I thought it might be lemon balm or lemon thyme, but it doesn't flower at all.

It resembles a small tree (has grown to 3 foot, but I had to cut it down as it died in the middle). The 'trunk' is about 1cm thick and pretty bare with 'branches' about every inch.

The leaves are a bit hairy and are all bunched up (like if you gather up the edge of material), really hard to explain!

The 'trunk' is dry brown and the branches eventually go like that the more it grows.

Can anyone help?

It is possibly a citronella geranium or mosquito plant view here: Citronella Geranium, Mosquito Plant

Unlike yours these seem to have flowers, but I had a variety for several years that did not bloom. It had the woody trunk with a long stem per leaf.

Hmmm. Here are a few more links for you to peruse. Geraniums and pelargoniums seem to have a wide variety of shapes (but they also seem to all have flowers).
Citrus

Grand View Geraniunm Grandens Once there scroll down to Scented-Leaf Geraniums-Lemon-Rose

Here is a link for information on other lemon scented plants.
Lemon Herbs | Plants

Geraniums have a very distinctive leaf-stem joint. Below is a link to a good image of that. If your plant doesn't match that joint than it probably isn't a geranium at all.
Google Image Result for http://gvgeranium.com/Scented%20geraniums/Mable%20Grey.JPG