beetroot, swedes, autumn plant, lettuce

okay all. maybe some of you can help me.

my swede has bolted. i planted some in raised beds and some in 2 foot deep pots on april 4th.

the pot plant swedes started to flower and produced no bulb.

the raised beds produced a bulb that was tiny in comparison to its huge huge leaves.
i pulled them up this afternoon.

looking at my 'encyclopedia of country living', the entry on turnip (i assume they're similar...) says to plant them a month before last frost (which i have down as may, therefore this should be ok? I bought these from a garden centre as seedlings) or in august (which i presume means they are pulled before winter).

so i can't understand what has gone wrong and wonder if anyone can help me.

also, i know very little about pollination - don't they require pollination to bolt?

BEETROOT:
I also have some beetroot in.
i'm concerned this might happen to them as i put them in april 4th too.
how would i know? how can i stop it??!


LETTUCE:
put this in last autumn under cloches. pulled it april and may this year and it tasted fine. however the growing guides i've read for lettuce say that it has a 5-day period where it is ready to pull up and outside of this it tastes rotten....is this true??/

FINALLY:

can anyone reccomend any autumn crop or over winter crop that i can put in and pull before May of next year? ideally i'd like ones that will fix nitrogen in the ground where i've grown my brassicas and bulbs.
i have one bed where i've grown carrots, one where i've grown onions and one where i've put beans and calabrese.
what would be ideal to replace them with over winter?
and can i have an overwinter crop that means i have space to start growing again after the frost next year?

 

That would be broad beans, if you like them. Personally I love 'em, but I know not everyone feels that way.