Assuming you get a full day's tuition included, then £350 incl an open pit day isn't too bad. I think I'd be tempted to look for another (cheaper) day where you can rock up to open pit, but pay an extra £20 or so for 30 mins instruction, which would be more than enough to get you started. You can then use the rest of the day as you see fit, and if you need some more lessons then you can always pay for another 30 mins. Bookatrack are ace at this kind of stuff, worth seeking out one of their days if MSV don't do that kind of thing.
That said, I will reiterate that £350 for a full day with tuition is really good value, and will definitely be worth it.