A cheap but heavy SS/Fixed which might be of interest is the Viking Road FX/SS (Circa £175). I've got one and done a few centuries on it and it is my used and abused commuter. For its price I've been quite surprised with it, the tyres lasted 2555miles before p'turing, they probably could have lasted longer but they are a bit of a biatch to remove/fit so I put new tyres on and almost exactly at 3,000 mile the freewheel unscrewed and I had to flipped the SS to Fixed. With maintenance I doubt it would have happened.
However, I seen a Spesh Langster for £160 last week 2nd hand you'll get much better vfm in the 2nd hand market.