I may be wrong, but i think the English longbow was around the 14th century 1300-ish.

I am lead to believe that the Welsh archers were top of their game in this era, but i don't think even they used a longbow as what we would consider longbow.

Have a look at the mod for medieval 2 TW: LastKingdom,
This was one of my favourite mods (probably my favourite!!)
i think that had some good unit rosters, its been a few years so i could be mixing the units up with mount and blade Viking conquest or the Saxon mod from the same team.