Hi,
There is a Marriott hotel connected to the airport by a tram where you could relax ( lobby, bar etc) at IAH which might be better than the landside area of the airport.
https://www.marriott.com/hotels/trav...ercontinental/
BA only has an arrivals lounge at LHR now ( they used to have one at LGW and JNB years ago)
Welcome to flyertalk!
Regards
TBS