I use Murrays Meat Market, a large, long established butchers @ the High St. end of Surrey Street open air market (also fantastic for fruit & veg). Incidentally, there is an excellant fishmonger just round the corner at the Crown Hill end.
What do you want to do with your steak? For grilling or frying, use sirloin, sliced wing rib, rump,or thinly sliced top rump. For stewing/casserole, shin, neck, chuck, thin flank.
for pies, chuck. For roasts, sirloin, silverside, fore rib, wing rib, top rump & topside. For braising, chuck, top rump, thin flank, brisket, & thin & thick ribs.