Cardiff Central to Brum Airport is 115 miles, don't believe the route planners because they route one over the Severn Xing when the route to take is the A449/A40/M50 link and with no toll to pay.
I'm out of date but going back a few years daily BHX offered something like 5 KLM services to AMS, 9 LH services to three different LH hubs, 3 Swiss services to ZRH, SN to BRU, SAS to CPH, a few AF services to CDG, Emirates to DXB with all the thru connections to Asia, Air India plus the IT Holiday and LoCo stuff and probably others that I can't recall.
I'd suggest that an extra 30 (ish) minutes each way in the car, whilst avoiding a hefty toll, isn't such a bad consideration!