
We live in that area and unless you are you are actively looking for them you are unlikely to see them, they are a shy retiring creature and tend to disappear quickly if they 'feel' your foot fall.
We don't even think about them, if you try and avoid all dangers then you're not going to be doing much else.
One of ours has been bitten, we didn't realise until some hours later when she collapsed, unusually she was struck on the shoulder so there was no swelling to indicate she been struck.
Contrary to popular belief hot days aren't the most dangerous, spring time is most dangerous when they first come out of hibernation, the venom is concentrated then and more potent, also Adders are a temperate snake so are adapted to cooler temperatures, they actually avoid the hottest part of the day and tend to do their basking mornings and evenings when the sun isn't so hot.
If you're dog is bitten you should ring the nearest vet straight away and warn them you're on your way, carry your dog and try and avoid your dog becoming excited and raising their heart beat.
My vets advice is never give any drug such as piriton, it's unlikely to have any real effect and may compromise the drugs the vet needs to give, the key is to get to the vets quickly and safely so medication can be started as soon as possible.