It depends on your outlook.
You have to put down a larger deposit on a BTL property, ive just done a quick search based on what you have said and there is only 1 lender showing based on you having a 15% deposit.
With a 20% deposit it jumps to....2!
You are looking at a 25% deposit before that jumps to about 10 lenders with decent interest rates. A smaller deposit and your looking at interest rates of around 6%.
The rent also needs to be 125% of the monthly repayments for the majority of lenders...eg your monthly repayment to the lender is £1000 per month, the rent needs to be £1250.
I would suggest you speak to a mortgage advisor (im happy to help if you wish), then you will need to do some research into how much property rents for in the areas your looking to buy.
Dont forget to keep money back for:
Lenders Arrangent fees - typically £1000-2000 per mortgage.
Solicitors fees - this can vary wildly.
Any work that may need doing.
Gas checks (need to be done annually).
Plus some sort of contingency money....I used to rent a house out, i popped round and didnt do checks i should have done as she SEEMED lovely...turns out she was growing marajuana and had put a 4 inch hole in a wall to allow ventilation. So it could be worth getting a management company who take a percentage of any rent (10% approx). After that i sold up.
Before you get into it though do your research, i was earning around £200 a month on 1 property so the money can be good. But i would definately think about it before hand. Tenents are a nightmare, you will have to do repairs occasionally - kitchen replacements, carpets etc (that reminds me, we had a tenent who moved in and we had put down new carpets 2 days before he moved in, when he moved out he said the iron mark on the floor was there when he moved in, we had the receipts to prove otherwise and he paid up but just a general idea of what you can get).