I want to buy a bicycle but there seems such a large choice - i dont know where to start help..?

I am 35 5' 2" tall and not experienced in cycling. I will be biking in country lanes and rough tracks and also on town streets very occionally.i live in the middle of the countryside and will be using the bike for recreation only - driving around the lanes and roads where I live. Halfords have a sale at the moment halford.ie and they have a huge choice. please could you look at the site and recommend one if money was no object and one under 300 euros many thanks