Most pants are generally roughly the same; so
S28-32 M30-33 L32-36 XL36-40 XXL41-45 XXXL46-50
Thats planets sizing guide, most other pants are the same / close to.
Jerseys are pretty much what ever size tshirt you wear plus 1 size, i wear a large jersey cos its fairly baggy on me, but i wear small pants cos im a skinny bugger.
Sometimes its best to go into your local shop and try some on