Any automotive/household clear will do. Krylon, Rustoleum, Plastikote and any other brand maybe exclusive to the
UK. For the most part a clear is a clear is a clear. "Hobby" clear coats such as Testor's or Tamiya is the same stuff as Krylon or Plastikote, just rebranded for use for mini's and then inflated price-wise 200 to 300% to sucker people into spending more money.
Also, try floor wax. Here is a link
http://www.swannysmodels.com/TheCompleteFuture.html to a website that details what the exact brand is and how it's used to clear coat models.
It can be thinned if need be or used straight out and clean up is easy and I've never had issues with it clogging (just make sure to run straight water or alcohol through
AB if you plan to spend a long time clear coating minis.