muntons ale yeast

found a couple of these packets in fridge. What would be a good beer to use them on???

I'd give them a go. Worst case scenario you have to re pitch.

they arent that old think about like six months

I'd toss them in the boil and use them as yeast nutrient.

Muntons yeast does not attenuate too well, you would be better getting a different yeast. You might want to save them to use for an emergency (making a quick brew with no other yeast available, or use if your primary yeast is dead.

If you use this yeast and you end up with a sweet beer, it is not always as simple as tossing in another pack to finish off the beer. Once there is alcohol in there, it is a hostile environment for the yeast.