I've spent a lot of time trekking in Canada, Britain and Europe (often in only parties of twos or threes) and I can honestly say the only animal to fear out there is MAN.
As long as you are sensible, follow a few simple rules and keep your eyes open, nothing is going to happen to you in the "wilds". The problem is that rural areas in this country are becoming rapidly suburbanised and landscape management decisions are being influenced by pressure groups such as dog-walkers (look at the recent shameful climb-down on the part of the New Forest National Park authority on dog walking). The only time anyone is likely to encounter an irate wild boar is when they have allowed their dog off leash and the dog has run off, disturbed a pig, panicked and returned with boar in tow to its owner. The whole incident is avoidable if we explain to a few interest groups (dog-walkers, the Ramblers, horse-riders) that they don't have carte-blanche to do what they please.
I'm all for the "re-wilding" of parts of the British landscape but I do think many conservation bodies are being naive about the extent to which this can be achieved. I can't see us managing to create an Oostvaarderplassen in the Midlands.
The landscape in this country has been shaped by human activity since the Mesolithic (12-14,000 years ago), European Brown bears were still in existence in the Iron Age and the last wolf was only killed in the 17th(?) century in Scotland. Whilst this is a very crowded country, I am constantly reminded in my landscape archaeology fieldwork of how empty many parts of the landscape now are; I can work in parts of Wiltshire for several days and not see another soul. Bear in mind that before the Anglo-Saxon period there was a far more extensive, less nucleated settlement pattern in southern Britain; people lived cheek-by-jowl with wild animals and they tolerated each other. Given our far more concentrated, nucleated settlements, there should be nmore than enough room for a few packs of wolves, elk, wild boar and red deer in today's landscape.