Or collect them & put them in a bird feeder. You could make a scoop out of the top from a big, plastic milk container & wash them into it with a pump sprayer?

if you don't want to use chemicals picking off is about your only choice. I don't think a soap solution would work. it is worth a try though. the birds and any fish [if you have a pond] would appreciate them.

I would try sowing Sweet Alyssum or annual Toadflax (Linaria maroccana) seeds nearby. Their flowers will attract and feed the tiny, stingless parasitoid wasps that lay their eggs in the caterpillars. Spinosad and B. t. are other organic remedies, but they may not be available in the UK. Encouraging a good population of earthworms will also help the Strawberry plants to resist the chewing...and make the berries tastier, as a bonus!

Would the blue garden variety of toadflax do the trick either please?
And does it work with all kinds of caterpillar, eg gooseberry sawfly?

If the flowers are small enough--less than 7 mm across. As for the sawflies, I don't honestly know, since they are not actually caterpillars: they are more closely related to wasps and bees than moths and butterflies. Presumably something eats them, but what those are and how to attract them is apparently my research project for the next week. :)

Thank you all. The plants are producing loads of fruit so I don’t think it’s affected them too badly.