A novice query, so thanks in advance for any advice.

Full of enthusiasm, we recently sowed some sweet pea seeds in one of those
seed propagator-things, with the clear plastic top (outdoors). We vaguely
thought they'd grow an inch or two during autumn and winter, then perk up
ready to be planted out in spring. However, they're now 5 inches tall and
growing steadily.

Will they keep growing all winter?
Should we bring them inside? (with or without propagator?)
Should we just leave them alone and let them completely fill the propagator?
Would a cold frame be helpful?

Cheers!
Lorna