Am I cutting things a bit fine?

Firstly - paragraphs

autumn-sown broad beans, followed straight away in the same ground with peas for drying - yes

early spuds could be harvested by June and followed immediately by planted-out tomatoes, Do you get blight? As you are increasing the chances by planting toms in the same place as the potatoes.

early turnips could be followed by late swedes, yes this will work.

Personally; the problem I have here is that you are following each crop here with a crop from the same family. If you want to double use your ground, then try following crops with different families.

Snadger has a system that he calls dual cropping; try a search on here for it.

What I do is to succession sow throughout the sowing season for each crop, and just put the seedlings in the next available space. I rotate my potatoes around the plot, and everything else just slots in around them. I never have just one sowing of any crop, as I like to extend the season as much as possible. Even parsnips I sow half the packet a few weeks after the first sowing.

This way, you'll find that on most occasions you can pick a space as one crops is ending to put a new different one in.

Also, remember that [for example] beans and peas are harvested up the plant, so you could sow new ones that are starting to crop as the early ones are ending; without actually digging up the early ones - just push the seeds in between the early plants [so peas inbetween the broad beans] and then chop the broadies down to the ground ones they are finished.

Please can I disagree Miss? I do it the way Stephen does - my onion bed for instance, is an onion bed for the whole 12 months. So I put over-wintering onions in, and then put leeks in the same bed, and the rotation begins the next year after the leeks come out... I think the tomatoes would be ok in the poato bed as long as they haven't been touched with blight. (And if they have, then it probably would get the tomatoes wherever they're planted out!)
If your space is limited, then having potatoes/tomatoes in 2 different places within one year is going to mean that the ground doesn't get a full 3 years between same crops.

NOOOOOOOO!
I rely on you 2 to agree on stuff. Now I'm going to get totally confused
I was already having a hard time getting my head round rotation and where things should go next.....What have you done!

LOL@ Incy

That's the thing with gardening, and growing Veg......everyone does it differently but the veg just keeps growing ignoring us all anyway

I don't follow the same family with the same family as I don't want to take the risk. However I have sufficient space on the plot to do a decent 4 year rotation with separate beds (in the same year of rotation) for potatoes and outdoor toms. I use any random space for additional courgettes and salad stuffs which I never seem to have enough of as I eat loads (the salad stuffs that is, have PLENTY of courgettes!). For example, where my broad beans are at the moment will have a squash / courgettes next summer, I don't have a massive areas of early spuds but they were followed by lettuce and the main crop didn't come out until far too late for toms. The old pea bed how has some spring cabbages in as well as some winter salads under a cloche. Works for me but you have to plan what works for you which, although sometimes based on what somebody else does, is unlikely to be the same.

Mine too. Crop rotation is tricky enough anyway, I try to keep it as simples as poss

I was following beans with peas, and spuds with toms, and turnips with swedes, precisely because they are the same families! It's all within one year, so it observes a standard four-year rotation. However, as Zazen says, I suppose I could just bung things in wherever there's available space: as long as everything gets moved regularly from year to year, I suppose you don't have to be too rigid about rotational schemes. (In fact, John Seymour, in 'The New Self-sufficient Gardener', which I've just bought, says just that.)
Thanks also for pointing out that the peas can go in before the beans come out. I've just had a thought: could I leave the bean haulm in place once the beans have finished, and use it to support the peas?
John Seymour also recommends the use of a holding bed, for putting seedlings in if their final position isn't yet available, so I will do that too: I've still just about got space for a seed bed and holding bed, so I'll dig one one tomorrow.