We were all told at the time during the lockdowns that LFTs were useless if you have an active infection, and that if you have any symptoms you need a PCR test. LFTs were solely for identifying and isolating symptomless cases among people who might have picked up be virus and might be infectious without any idea that they might be ill.
Yet suddenly once they wanted to wind down the publicly available PCR testing the narrative around LFTs was changed. Their efficacy didn't change, they have never been reliable if there are symptoms.
BUT it doesn't matter. All the lockdowns etc was to slow down the spread so that there wouldn't be a huge spike of serious cases beyond what medical services could cope with. It is endemic now and medical services aren't going to get any more overwhelmed than the general level they are just expected to cope with in the context of normal tory underfunding.
If you have any kind of infectious bug stay at home while you feel unwell. Doesn't matter if it's a cold, flu or covid the action is the same, so no need to know what it is. If you feel well but have any suspicion that you might be infectious eg if you have been ill in the last few days (but feel fine now) or if you recently had contact with someone unwell, then for God's sake wear a mask to protect others. This simple rule also should be applied irrespective of whether it's a cold, flu or covid.
Waste no more time or money on LFTs. Their only purpose is to provide somewhat unreliable evidence that you aren't currently carrying a symptom less case, which you only need if you are visiting or work with someone Clinically Extremely Vulnerable.