Now, just to warn you I haven't confirmed this works yet, but if it does it will only be valid until tomorrow so I thought I would get it on here ASAP for those that are willing...
At the moment M&S are doing their Dine in for Two for £10 - bottle of wine, side dish, main course and a dessert. I think this is a pretty good deal on its own. But,
When you scan all the items in at checkout, it discounts your purchase to make the total £10. However, your total bill without the discount is approx £18, depending on what combination you get.
In my local M&S, they currently have loads of £10 off £50 spend vouchers at the checkout. My guess is that if you scan in 3 lots of the meals for 2 for £10, bringing a total of £54, it will allow you to discount the bill with the £10 voucher and then add the reductions for the 3 Dine in for Two. This would bring your total bill to £20, for 3 meals for two.
Further still, and I've tried this out so can confirm this works, they currently have 25% of 6 bottles of wine. Any wine you buy in the meal for 2 deals counts towards this, so if you want to, you can add a further 3 bottles of wine to your basket and get 25% off all 6 bottles. So add another 3 bottles of £5 wine to your basket, and you will get another reduction of £7.50.
£27.50 for 3 meals for two and 3 extra bottles of wine!
I'll confirm this later, but I won't get to M&S until later this afternoon so if anyone can confirm this before I'm sure others would appreciate it.
(I found the £10 voucher in my Colliers Wood branch, but hopefully they are nationwide, in a book of 4 vouchers 1 valid each week over the next month.