oil pressure light- check the plug is connected on the oil pressure switch on the back of the engine

temp gauge- check the temp sender unit wire is connected on the front right hand side of the head if so try a new sender there only a few quid

battery light - could just be a blown bulb other than that try and check the wiring for any breakages

i take it its a mk3 escort, if so the dash light module is behind the dash in the centre, if u remove the dash'es centre speaker/centre heater vents then you should see it, its a yellow ecu like box, u can pick them up on ebay quite cheap now and again