whats this on my brocolli? help please

I think those are eggs of something undesirable. Squish them (if you don't mind that) or wash them off. Lovely looking plant - you sure there aren't any heads forming in there?

looks like the start of whitefly.
Scrape them off with your fingernail, and plant some French Marigolds around the brassicas to deter whitefly.

dont think i can scrape them off coz they look like they are embedded into the leaf... or maybe i was being squeamish hehehehe will try again. does anything else deter whitefly? we dont have much room around the brocolli to plant anything, didnt realise it grew so big!

ive just read that they can cause leaves to go brown... do you think thats what could be on our beetroot as well (feedback on here said they looked overwatered)? argh! please dont eat my first grow your own crops!!

I think Two Sheds is right, the marks you see are where they have been sucking sap already, the blobs are the eggs. Or the eggs are unconnected with the marks, which might also be due to sun shining through tiny water droplets and scorching the leaves. Either way, ignore the marks, and get rid of the blobs, or you are likely to regret it. They are not there just because they like the view !
If you find that you suddenly get wriggly paths of the greenless patches, then that is a leaf miner - an insect which lays an egg inside the leaf, the grub that hatches out then chomps along between the cuticles leaving a trail of destruction behind it, again it is a case of get it before it gets your food.
It is just one of those things, but when the plant is that big it will not stop you having a crop. The first year I grew brassicas I had leaves like lace because I didn't have netting and the cabbage whites had a field day - but they kept me going all winter anyway.
As long as you have a decent ecosystem full of predators, the numbers will not get above a certain level. So no need to panic !