The listing on the official website of the British Monarchy specifies that the job in question – based at the Royal Mews at Buckingham Palace – entails working "as part of a busy and supportive team tasked with driving members of the Royal Family, Household officials, guests and official visitors." That means being around some highly distinguished individuals, for what it's worth, but also getting access to some very rare machinery, the likes of which most people will never get close to: namely, the Bentley State Limousine, a vehicle designed and crafted in Crewe, based on the Arnage, specifically for use by Her Majesty and members of the royal household.
Don't think that the proximity to one of the wealthiest families and heads of state in the world means the job would be what you might call "lucrative," though: it pays around $35k per year, which includes meals but not the mandatory lodging, the cost of which is deducted from the salary. Of course it is a government job, of sorts, so it comes with full benefits. And then Queen Elizabeth II has been known to drive herself around from time to time, when the mood strikes (and with impunity), so there could be a lot of downtime, too.