I'd recommend the Hyundai Kona Electric. I drove it recently and it's a really good car, with a range of up to 300 miles and 170mm of ground clearance. The biggest problem you'll have is sourcing one - it's brand new, with Hyundai only taking orders via its Click to Buy website. Alternatively, the Jaguar I-Pace is also an excellent electric vehicle, with a 298-mile range and air suspension so you can increase ground clearance when driving down your forestry track. It's surprisingly capable off road but quite expensive - starting at £58,995 after the Plug-in Car Grant.