I'd take a look at those mentioned above, they are all good choices and I would add
Driftlimits in Hertfordshire to that list - Full disclosure, I have worked with these guys in the past and know the venue and instructors well. I've never been a customer on a drift experience with anyone, but I've been to / driven at most of the venues in the UK that are used for experiences.
I also know Driftlimits have up to 50% off at the moment.
Anyway, loads of price brackets, loads of cars from basic to highly modified and a dedicated drift track at the venue which will genuinely see you working your way up to entering drifts at 50mph+, faster if you can keep up with it - I think this is something unique to their experiences. The track is dry unless it rains, so no deliberately wet track.
I'd be
very wary of basing things on "time" - lots of experience days (and also experience day retailers like red letter day etc) quote various time frames, but all of this is relative when you're at the venue - this is even something you will see even with vendors selling Driftlimits products. Some experience days include everything from the briefing to tyre changes in their time quotes, some don't, some quote the amount of time they expect you to be at the venue in full etc, some the amount of laps you do (which means you might take 6 hours to do the laps or 15mins depending on how you drive etc) - it can all be a bit confusing and misleading and I almost feel like its left deliberately unclear by some vendors in order to sell something "bigger".
Also be aware that most drift experiences in the UK are held on stock car ovals, in paddock areas or on runways. Though some of these venues are at racing circuits, like Brands Hatch and Rockingham, you won't be drifting on the circuit. Firstly, there are very few circuits that offer on track drifting to anyone and secondly its far safer you have a big open space to learn in. Don't be fooled by the location, it will still most likely be a coned out area.
You'd be better basing your selection on your budget, location and the specifics of the tutoring. Don't be put off or impressed by those that bash other days for what cars they use, it isn't a bragging competition and most drift experiences use the same range of vehicles you'd expect to see at a practice day - from mx5s and BMWs to S14's and Skylines. If someone says an MX5 isn't capable they're talking out their ass, one of the most well balanced, responsive and
fun cars to drift.
All experience days are "1-2-1", theres only two seats in most of the cars. All experience days cover the cost of the car, fuel and tyres. Again its just marketing talk. You will almost certainly be a part of a group however, even if you do have a car and instructor to yourself for the day.
I know Driftlimits offer additional track time you can purchase on the day, and its really reasonably priced - so even if you get one of the shorter sessions you can always budget a bit extra to get more laps if you feel like you want them.
As a rough idea, another 10 laps (about 15-30mins driving time depending how much you spin, see what I mean about time?) in an MX5 will cost you £45. I would advise you book a session before lunch if you plan to hang around and do more driving, it will give you ample time to do whatever you want.
All of their packages other than their drift car collection see you start in an MX5, though as I said, you have the option to do all or some of your session or extra sessions in anything from M3's to a turbo AE86 to a V8 powered geomaster S14a.
There are also, as with many other experience providers, hefty discounts on their packages for christmas. Spending nearly £600 will get you an awful lot of driving with almost anyone you go with.
Hope it helps.
Here's a link to a completely unedited 4min video of the Driftlimits venue, shot from a drone. You can see the layout and size of the circuit and people in MX5's and their V8 S14 learning.
Track overview
Driftlimits Facebook