If you don't mind limited headroom and porch, the Ferino Ultralite from Decathlon is excellent. When I first got it, I thought it was a tad coffin like, and in many ways it is, but for all that, it is cosy and, best of all, high quality and bomb proof.
http://www.decathlon.co.uk/EN/lightent-3246909/
They only seem to be showing the red here, but you can get it in slate grey. As I said, limited porch and headroom, but packs down really small and is only 1.5 kg.
I also have a Highlander Forces 2, which is also a great tent, but with much more space. It's bombproof, ultrastable and really practical (other than inner pitch first). I replaced the poles in mine for alu from Decathlon (about £30 for two sets). The Forces 2 usually goes for about £35, so that's £65 for a tent that weighs in about 2 kg. There are no real flourishes to it (I believe it was designed for the army) but a great design, free standing, tons of headroom, a good sized porch and even a door you can rig as a canopy should it be raining. It is prone to condensation given the right (wrong) conditions, but if it's not raining, I've found leaving the fly door open cures it pretty well.
Of course, if you want something good and really cheap, look on ebay for a proaction Tigerpaws. They come up every couple of weeks or so, even the more sought after green version. Usually go for about £25, about 2kg, and a great little tent, by all accounts, though there are some niggles with the design (zip too tight to close when the fly is tensioned fully, and condensation - from memory).
