alternatives to leathers, there are loads mate. i used to ride in jeans, though i did have a leather jacket.
go to any decent clothing shop, and they will have a good range of fabric jackets and trousers. actually the fabric ones will look more appropriate given the bike your riding, and they are a load more comfortable.
you can also get kevlar reinforced denim jeans, i have a pair and they are great. Ive also tested them on a road a few years ago, i had all my skin, unlike the pair of regular jeans i tested a few years earlier!
The kevlar ones arent going to give you any rain protection though, so if your going to commute, i would suggest the decent fabric 2 piece sets, of a decent fabric jacket, and a cheapish one piece waterproof suit