All the advice about doing your research is good but I'm amazed that anyone these days would even think about an RICS valuation.
Over the past couple of years in terms of property hype, RICS valuers been running with the pack and from what I have seen have produced a lot of wildly optimistic valuations. I have seen many situations where they have got it spectacularly wrong and the original buyers now face massive losses selling into the current market. It follows that there are a now a number of cases where RICS valuers may well be sued for professional incompetence.
If you want to buy property to rent out, BMV doesn't even come into your decision. There is just one consideration and that is, after taking into account all you costs, whether or not it generates a positive cash flow. Buying cheaper and getting BMV to obtain future capital appreciation is a bonus and subject to timing differences. Obviously, you can choose when buy but the most important thing is being able to choose when you sell. If your investment is cash positive, then unless there are some other external reasons for wanting to sell at a particular time, you need never be a forced seller into a market that is running against you.
By the time you add in the initial fees, you're going to be paying in the region of 7.5% for your mortgage, so look for provable rental yields of 8% and more, especially if the property is ex local authority. For ex la you need to price in the higher risk of getting poor tenants. Believe it or not, the odd one or two decent properties are now turning up at auction that can be bought where yields of over 8% are achievable (I have just bought one) and there's definitely more on the way. But be careful to avoid the city centre 2 bed apartment wastelands where half the properties are still empty because the rents being asked just aren't achievable.
Get at least, an 'in principle' approval for a mortgage and start doing your due diligence. Also, if its a repossession, be prepared to move fast. There are one or two mortgage lenders that can move quickly, so consult your mortgage broker to find out which ones are best. Also be aware that repossessions bought through auction often require 14 day completion, so don't get caught out with deadlines you can't meet.
If you want to buy a 'packeged' BMV deal, study all the aspects very carefully and don't just believe what you are told. Go and find the answers and prove them to yourself. Some sellers will, for a number of different reasons may genuinely sell on good leads but again, do your own homework thoroughly.
Good luck!
NickHam