you don't need the large oil filter and cover, but you do need the correct size filter for whatever cover you have. Both the long and short work equally well (it's been covered several times if you do a search it may come up)
as for parts, worth trying Griff. I always get my stuff from him, some bits he's more competitive on than others, but you should phone round anyway- he's defo one to put on the list, at least you know you'll have it next day delivered!!