>>314167The city I live in has a few outdoors shops like Mountain Warehouse and Trespass, I imagine most places will have at least one of these or a Millets or Yeomans.
You definitely want to find a store and try on a couple of pairs (as opposed to shopping online). Take some walking socks with you or ask if they have a pair to try on while you test the boots. They'll usually give you a bit more guidance and attention at an outdoors shop than other clothes chains, even the big national chains like Millets have always been good in my experience. Take your time to tie them up properly and have a walk around in them, making sure they're really comfortable and fit well. You don't want your foot sliding about (leads to blisters), but you also don't want your toes crushed and foot going numb.
As for picking some out: Leather over suede is my personal preference because it's easier to clean the mud off and you don't need to buy some fancy branded "shoe protector" nonsense. Just plain old shoe polish will protect them. Look for ones with decent waterproof *-tex (gore-tex, but a lot of brands have their own branded version of it, like tres-tex for Trespass shoes) material on the tongue. You wanna be able to walk through a ford or bog without getting wet feet, and another thing to help with that is a high heel, which also lends ankle support.
You can hit all these requirements for around the £60 mark.