OK - it's not too bad, but this is what I would do:
Oriental vegetable and smoked chicken salad, herb croutons, sweet chilli and ginger dressing
Ditch the croutons, definitely. But the tricky thing is avoiding the dressing as that will be very carby. See if you can have yours served on the side. if it's a sit down meal that's likely to be tricky, as they will be plating up on the kitchen, but if you could email them in advance or grab one of the waiters/waitresses as you sit down that might work
Pot roasted shank of lamb, hotpot potatoes, Savoy cabbage with crispy bacon, mint gravy
No potatoes! Ask for extra cabbage if possible. Try and avoid the gravy as well, as it will most likely be thickened with flour. But not a bad main course for low carbing.
Pot of chocolate, lemon shortbread, berries and cream
In order of preference:
cream
berries
pot of chocolate
lemon shortbread
The chocolate might be OK if it's made from dark chocolate. But probably best - if you have the willpower! - to just go for the berries. Again, you could always email beforehand and ask if you could just have berries and cream.
But above all, enjoy yourself!