Given that you are in the UK, Nicholas' advice seems spot on. If you can live with just 35mm, you might consider a Leitz V35 enlarger. In the US, you can pick them up for around $300 with lens and they are very nice.
Do make sure you align the enlarger properly. Aligning basically means that the negative is held parallel to both the lens board and the easel. There is always some way to do this (but some are really difficult!). This is probably more important than which enlarger you get. Also, make sure you get a good lens. Most modern 50mm f2.8 lenses are fine for 35mm (Nikkor, Rodenstock, Schnieder). One more thing....make sure that you get the negative carriers and lens/lensboard with the enlarger. Getting the needed accessories later can add up.