Yes, you've planted way too early I'm afraid. Even if you plant them out and protect them with fleece I'm afraid they won't thrive as runner beans hate the cold and frost will completely kill them off. Beans are not too expensive so to avoid total disappointment I suggest you sow another batch around the first week in May. They germinate quickly and will soon catch up. If you don't want to do this and are forced to plant them out, don't do until until you've bought a large length of fleece and have wrapped it completely round your runner bean pole structure to protect them. Then in early May, if they're not surviving, plant new beans beside them in the soil and once they've germinated, get rid of your lanky beans, otherwise you'll never get a decent crop unfortunately.