I'm going into second year and I was in Mason Halls on Meal Plan last year. Just to give you a bit more of an idea about Meal Plan...
We got around £45 per week to spend on food. Your money ran from Saturday morning (when your card was topped up) to Friday night, when any remaining balance would be cleared and you had a fresh £45 for the next week. Your flatmates will also be on Meal Plan, but your block will probably be mixed.
At Shackleton, you could spend your money on Infusion restaurant in the evenings, or at the Deli at lunchtimes for a panini or sandwich. Also this year they launched Pizza Shack for the evenings too, where a margherita pizza for example only cost £6.95. Great if you have friends round, and my friend and I sometimes shared a pizza one night where I paid, then she would buy dinner for me another night. There is a Costcutter in Shackleton and in the university centre, but unfortunately neither accept Meal Plan.
At the weekends, things were a little different. You could go at lunchtime to get a sandwich or panini etc, but Infusion didn't open in the evenings, so you could either get a pizza from Pizza Shack or cook for yourself. I usually bought a panini or baguette for the evening at the weekends.
On campus, you can spend your Meal Plan money at every university outlet. This includes med school, the cafe in the learning centre and the food court in the university centre. Being a medic, I didn't really try much food outside of med school, but apparently the food court was very popular (if a little expensive if you weren't on meal plan). I'd say generally food on campus is overpriced for what it is. In the students union building, there's a little restaurant and a Subway, neither of which accept meal plan though.
The great thing about Meal Plan was that it really took the stress of cooking away. I'd recommend it for first year, just because you're going to be trying to adjust to living alone away from family, and you want to focus on settling in and getting used to university life, rather than worrying about feeding yourself and ensuring you have enough food to last you. Although it is quite expensive (none of my self catered friends ever spent £45 a week on food!!) it's really just about convenience. For first year I'd say it's useful. Also, if you had any money left over, Infusion also stocked things like milk, bread, fruit, yoghurt, cereal, porridge etc throughout the week, so you could use your meal plan money to get essentials like that.
But just be aware, even if you're on Meal Plan, you will have to cook at some points. Eg. if you're too tired to go down for dinner (bit of a trek from Mason and Maple Bank), or at the weekends. Need to be careful with budgeting too - since you get your money at the weekend, you have to try and ensure you make it last till Friday, or cook instead.
Hope that gives you a bit more insight into Meal Plan