Slitherine

Any recommendations for these in 15mm?

Not much info on foot troops in Osprey German Medieval Armies but there is a picture right at the back of a man scaling a ladder in a 'kettle-helm'. But it goes on to say these were used in sieges

Essex do a good range of spearmen of the period:

Well, the description in the army list is shieldless with heavy spear. Essex Low Countries Pike look overdressed, and I'm aiming for a bit earlier period.

From that description, check out Peter Pig's Wars of the Roses Spearmen?