i work with horses, if you consider they need shoes every 5-6 weeks(50-70quid), livery, feed,bedding,turning in/out, dentistry, insurance against vet bills ( or vet bills), without considering the bridle, saddle ( around 5-700), rugs for winter, bandages for shins, plus time to break in and cost of the horse itself and of course a hat, whip, boots and lessons........
You could average a total cost of around 600 a month, or just call it a money pit.
Or you could go to a riding schoool, pay 17-25 quid for around 30-40 minutes tuition and be loaned all the above for free, then going on a