Hi my surgeon have told me to get a post op binder. A lumbar binder or something, they said to get it from a sports store like JD Sports but I can't find them there. Any ideas on where to get one asap please? Thanks.

I would try Underworks. 

After a quick search, I found this:

www.underworks.com/men-post-surgical-vestsAC

I normally wear Underworks' tri-top binders, but I've not had my top surgery yet.  If you have a large chest (mine is a D, almost DD cup), its a great place for binders for us larger-chested men.

Good luck bro!

Ryuichi