Are you killing your plants with kindness?
You seem to have spent a lot of time and energy on feeding them, perhaps unnecessarily, but not made a serious effort at dealing with their enemies. Beans, carrots and probably salad leaves should not need feeding. By feeding them you are encouraging a lot of soft leafy growth which pests think is just fine.
Are your home made composts fully decomposed? If not, they will rob the soil of nutrients in the short term. It sounds as though your potatoes were starved.
Your courgettes, cucumbers and aubergines are not getting pollinated. Courgettes should not be in a greenhouse, it is not necessary and might prevent insects getting to them. Aubergines are notoriously difficult, I suggest you stop trying until you have got easier crops to work. (I have been growing vegetables for over thirty years and have been modestly successful with aubergines for the first time this year).
I am not sure why your tomatoes are not ripening, assuming the plants look healthy and the fruit has reached a decent size. Try picking a few and ripening them indoors. I understand that small plastic greenhouses are difficult to manage as they easily become either too hot, too cold, too damp or too dry.
Everybody has bolting radishes at some time - and rotting salads as well. Take off the plastic bottles as they will increase humidity and make matters worse. Pea plants always end up with mildew - my mangetouts are long gone and my huge sweet pea plants are now milky white and will have to come out soon.
Any kind of cultivation requires ruthlessness. KILL slugs, do not save them up and take them on a holiday. If you wish to be strictly organic (though you use Growmore) you will end up doing a lot of murdering by hand. That is what the experts do. If this is not in your nature you will either have to accept a little chemical assistance or realise that vegetable gardening is not for you.
Gillie