Hello there,
Firstly Cellulose thinner is our name for laquer thinner, and white spirit is a kind of enamel thinner (not as good as humbrol etc) , you can buy this stuff in bulk at DIY stores (home depot, wal mart etc to you guys).
Halfords is a range of stores we have over here in the UK that sell lots of stuff for cars (including paints, tools, batteries and stereos) as well as other stuff (camping, cycling) . I`m not sure if you have a store like this over the pond, but it`s similar to Parts America or any store like that.