There’s an upcoming trackday with MG on Track later this month at Silverstone GP circuit. It’s a sessioned day of 20 minutes per session, with MG on Track having one of the three sessions per hour.
This is a rare occasion to do a trackday at the circuit for a reasonable price. In the past couple of years, Silverstone has stopped third-party trackday organisers running trackdays on the circuit, so the only option is to book a trackday with Silverstone directly and they’re typically £450+! This is £290 (passengers can be added for no additional cost) so it’s a great chance to experience the circuit at a cheaper rate. It’s not quite £99 Bedford Autodrome territory but the driving standards are increased to reflect that 
The trackday event page says that this isn’t open to first time trackday drivers for contractual reasons.
I attended this trackday last year in my lightly modified Mk1 (standard power, coilovers and exhaust modifications) and it was a great event with some lovely cars up and down the paddock. Last year, the other two groups were Lotus on Track and some posh trackday club with some interesting machinery to go and look at.
There are some spaces left so please take a look and if you’re interested, please contact Dave Pearce (DaveP@mgs-on-track.com) to enquire before booking. They’re happy with sensible MX5 owners to attend (they don’t want racecars testing or highly powered cars!), but as it says at the bottom of the event page, they want to be contacted before you book to check that they’re happy.
Link to trackday: View Event- MG's On Track