Which meringue is safe to eat without baking?

Considering the three main types of meringue (ignoring the 'vegan meringue' made with aquafaba), you would not eat French meringue without baking because it contains uncooked egg. While salmonella-contaminated eggs are increasingly rare in most (Western) countries, including the UK, this is probably wise.

Italian and Swiss meringue are both cooked to some extent; the former by whisking a hot sugar syrup into the eggs, the latter by heating the eggs over a double boiler. Unless you are measuring the temperature of your mixture and the time it takes to cool, you cannot be sure the eggs will be 'officially' safe, i.e. pasteurised.

Given you are in the UK, you will most likely not experience any negative effects from consuming raw eggs (see Chris H's answer for more details on this). If you want to be extra cautious, you could make any of these meringues with pasteurised eggs (recommended by the FDA in the US, where salmonella infections are a little more likely), after which any meringue would be safe to eat raw.

As you're in the UK, they're all safe. Raw egg is safe according to the NHS

Because of improved food safety controls in recent years, infants, children, pregnant women and elderly people can now safely eat raw or lightly cooked hen eggs, or foods containing them, that are produced under the British Lion Code of Practice (regarding hygiene and especially salmonella).

This doesn't apply to all other countries, but it's worth checking in many EU countries, where dishes containing raw egg are traditional (such as chocolate mousse and tiramisu). I've failed to find a single reliable source covering many countries, but Finland, Sweden, Denmark and Norway are essentially salmonella-free. I read enough French to make sense of some sources, but can't find anything definitive more recent than 2013 in which products made from raw egg are advised against for high-risk groups, but generally acceptable; in particular recipes assume that pregnant women will be avoiding raw egg.