is it lpg?
if so i have heard good reports about the lpg plugs ngk do, but the gap on ordinaries need to be set at about .75mm for lpg or standard its .9 i think.
oil air pollen filters are pretty much run of the mill, again you get what you pay for,
also when you remove the oil filter, above is the oil pressure switch, if this has and oil around it you might aswell replace it, about £10, its a cow to get at but it will leak eventually and a new one will save you the hassle of getting under there again, if its 27mm its original if its 22ish its a new one so shouldnt leak!!
plug leads, get the magnecor type and the bigger 9mm ones are best in my opinion, standard is 7 or8 mm i think.
dont forget to do water aswell, maybe an idea to get a chemical treatment so it will flush easier and more effectively.
oil, i cant remember the spec of it but again whatever the best you can afford, £40 a gallon might seem expensive but the engine is worth about 2k so whats £40????
it is really as simple as a fiesta to service but there is more of it!!!!