I've got an upcoming flight from LHR to IAH (in W), and then a United flight IAH to SAT, with a 3.5 hr layover at IAH (all on the same PNR). From what I've read I don't think I'm entitled to use the BA lounge at IAH (i'm BA Silver), but just wanted to check that is the case?

If it is, can anyone recommend a good place to spend 3hrs at IAH?