My mum won't consider the perfect horse?

I understand the situation that you are in but you have to remember all the other things. Who has to pay for the horses feed, tack, vet bills etc. Even though people consider buying a horse the great expense but actually maintaining one is much greater. Also will you always have time to care for it with friends, exams, and holidays? Your parents are also probably worried about keeping your life in balance. If it is a twenty minute drive it will take at the very least 2 times as long meaning there and back would take one hour and twenty minutes. Would it be possible to take public transport especially if it is available and free for people your age? Furthermore after caring for the other horses would you still have enough time to travel there get home and be able to do your homework, sleep and eat. On weekends would you still have time to see your friends. Ask your mum if it would be possible to take your instructor or another experienced person with you to make sure that this horse is even a possibility. Also you could see if you could lease him with another person so you would have less responsibility.