We have the charts to tell us what to do, but step one is to work out where you are on the charts. In domestic, we don't tend to use stickers on the devices to say DB1-6 so we know where fed from. The last EICR may help, but
they tend to be somewhat lacking as to telling us even how many sockets there are. So you have to try and find out. I had with my dad's house a FCU feeding another FCU, once we get DIY we need to do a lot of testing to find out what we have got.
So start point is the consumer unit, the circuit origin, so we can have a fuse, MCB, or RCBO (MCB and RCD combined) and if not the latter also a RCD likely feeding the MCB, without either a RCD or RCBO we need to look for a RCD FCU somewhere for a new socket we need RCD protection.
Once we have found the feed, we can lock off the supply
and use a non switched tester which does not require batteries to test it is dead, then test the tester in a proving unit. OK, I know that is unlikely with DIY, but you must realise you're not following all the procedures so need to be very careful. Be it a non-contact tester, a neon screwdriver or multi-meter, you need to test, a table lamp may show if current can still flow, but it will not show faults like line and neutral being swapped.
If it seems to be a ring final, then you need to test to confirm it is still a ring final. When you see an electrician do the work, it seems so easy, but he does have test equipment which DIY people are unlikely to have, so need to be a lot more careful. I tend to treat it as live, even when switched off, remember a MCB does not normally switch the neutral. So a neutral - earth fault will trip the RCD, the MCB is NOT an isolation device, even if we tend to use it as such.
But your question is like asking "Is it safe to cross the road" and we could look at the lane we live on and say yes, but you're trying to cross a motorway.