You must try on climbing shoes. It’s impossible to do it mail order. They’re all different shapes and sizes and a size 6 in one brand will be a size 9 in another.
First pair I had were, uh, Boreal I think. But, trust me on this, go to a proper climbing shop and get advice and help from an actual climber. When I bought my most recent pair, as an experienced climber and knowing what I wanted, I must’ve tried on every pair in the shop pretty much before making my purchase.
Any other climbing gear, you can get Internet advice, there’s no such thing as bad climbing gear for fairly obvious reasons. Shoes, no way. Seriously, it’s worth a couple of quid premium to get something suitable that fits.
Generic advice. Slip lasted shoes will stretch maybe half a size; board lasted will not. Shoes should be tight but not painful; specifically, any pressure points and it’s the wrong shoe (or wrong size). Some people will tell you that if it doesn’t hurt it’s too big; for a beginner, this is bad advice, walk away if you receive it; painful shoes won’t help your climbing, they’ll just make you dread it.