You'll need more than a handful of sheep with lambs to keep on top of 2 acres in this weather, wherever you are and however you manage it!
Personally, I would think that at your numbers and stocking density, worms would not be very likely however you manage your paddocks.
Does 'wasting' grass matter? Will you be short of hay in the winter? If so, then can you get someone to come and take a cut of hay off for you? If, on reflection, it doesn't matter, then let them have a lovely time wandering from paddock to paddock in luscious long grass for a couple of months. It'll soon be short again come autumn
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One provisos being that you are very on top of flystrike prevention and watch. Sheep in long grass would be more able to hide - and hide symptoms - from you
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Another option would be to get someone else to bring on some cattle or ponies to follow the sheep. They'll help with worm control too, as well as helping you make use of the grass.
Or you could get some store lambs to fatten alongside your ewes for the summer.