if OP wants to ride British bridleway with rust jammed farm/field gates, he might need to consider carrying the bike over the gate... When looking, I was considering classic Aluminium frame 1x11 or 2x9 and bit the bullet and went for carbon because of these gates...
Boardman are good bike (mate of mine loves his 8.9E) but since OP is in the UK and before heading to Halfords, planet X freeranger might be an option too.