Sorry you are having such problems and I am afraid there is no rain in sight for quite a while. Gardening is not easy, look at the difference with last year!
I suspect you have some rather woody green waste compost? Once dry it is indeed difficult to wet and needs a lot of time to soak up moisture, such as when it rains. It sounds like you have done a lot to conserve moisture, and don’t worry about not seeing worms as they migrate downwards in heat.
It shows the advantage of starting early, especially with green waste compost which needs to be in place and fully moist before the end of March. I made a bed with some in February, swet compost on wet soil, but the onions are much smaller than in the next bed which is cow manure and soil. Also the green waste compost is good when used as 50% of a bed-fill with 50& manure.
If rain is forecast any time from end July, it is too late for carrot & beetroot but be ready with seeds of spinach, rocket, kale, spring onion, oriental leaves.
Another watering question, from a gardener who is on the mentoring course:
"What are you watering? I understand you don’t water anything apart from watering them in and your lettuces . What are you doing now we have not had rain for so long?"
Well I am doing some watering, mostly of lettuce to encourage it to flower later rather than sooner, as well as give more leaves. Recent plantings of lettuce are good to water every three or four days to keep them growing fast.
Tall peas appreciate water because of their high number of leaves, making them transpire more, and watering helps them to crop for longer, as well as giving juicier pods. Today I watered celeriac, celery and also some leeks I had planted and watered in a week ago. More veg would enjoy water but it is expensive and plants such as Brussels sprout seem able to go semi-dormant for a while, not for too long to be sure. I am watering some courgettes which are near a cherry tree, little and often so the tree can’t grab it all.
I am not watering winter squash or climbing beans, not yet anyway. Onions are alright because so close to maturity. Parsnips are sending down a deep tap root so leave them be, but carrots wil swell nicely if watered.
In greenhouse and tunnel it is every two days at the moment, far more than usual, because of this unusual weather – not only the hot, bright sun but dry air and we have a wind almost every day.