It was clear it was going to be needed. Far more could’ve been done to prepare people to work from home, get food deliveries up and running, etc. France and Spain both went into lockdown earlier in their outbreak as well. Well only know when we see how the NHS copes over the next month. If the aim is to lockdown to stop being over capacity then we will know if we did it too late.
As much as I understand the not wanting to be in lockdown any longer than necessary argument the state of other countries does suggest we've left it late in the day to do especially with our generally poor compliance with what we were asked. Does also seem a lot more could have been done to prepare systems to cope with and the overall plan could have been laid out without giving dates. Anytime the government have asked the government questions about future measures they've been very non-committal and that gives the public mixed measures.