The last I checked, you could order a pack (7) a day of LFTs online, per household. Or collect two packs, per visit to a pharmacy/other distribution point.
The first seems limited by delivery-slots (there were problems with that, not sure about right now), the second by what's actually in-stock (depends on how many 2-packs-per-visit have been made).
You're only supposed to get them if you're asymptomatic[1]. Hence my disinclination, given my now subsiding[2] 'cold'... Maybe when it tails off completely I'll join the rush. Otherwise (or for travel) you're directed to get a PCR.
I think anybody in the UK can get at least advice from 119 (if there's not manning/demands issues!). But go through the appropriate bit of gov.uk or <region.>nhs.uk and I'm sure there'll be a decent facsimile of the latest advice without tying up anything more rhan web-resources in the process.
[1] For most of the UK "twice a week", regardless. Which I've been definitely shirking at, back in the more halcyon days of self-complaisance, so if there's supply issues it aint my fault. Enlgand suggests "before you go to a more hazardous situation" (whether mingling with those more likely to pass it around, or those more susceptible if you do), but no sign that's meant less speculative hoarding by the hordes and other hoggers.
[2] Which I'm sure it is. Complicated by the fact that a PSU blew in one of my machines, this morning and between the lingering remnants of the 'magic blue smoke' it let escape (with such a flash!) and the clouds of dust I disturbed (during the convuluted process of moving, dismantling, remantling and replacing the equipment concerned) there's a bit of an atmosphere in this room that I've not yet properly vented. For such a surprisingly easy repair, it can be somewhat unpleasant to do - given the infrequency of its necessity.