This is a complex question but the easiest way to get a decent estimate is to go via the purchasing process. There are many hidden costs that a first time buyer may not be aware of.

First Time Buyer Costs

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Sourcing Fee

Most agents do not charge a property sourcing fee, well not the high street lenders. If it is a private deal or from a specialist they may ask for a fee however in these cases they should justify their charges by the extent of savings made. If this is a case and you are getting a better deal than the market you do not need to budget this as the saving will balance the fee and more.

Mortgage Arrangement fees

These typically vary from lender and even with lenders depending on the products. Sometimes the better the interest rate or higher LTV the higher the arrangement fee. In many circumstances the fee balances out savings in the fixed term.
However these are almost always added on to the loan amount so will not impact your immediate cash flow.
Occasionally the lender may ask to pay a surveyors fee

Stamp Duty

As of 24th March 2012 the stamp duty holiday is over for first time buyers. For property up to the value of £250,000 (most first time buyers will fall into this bracket) the stamp duty is 1%. Stamp duty is payable up on completion and will need to be sent via your solicitor.

Legal & Search Fees

You will need to keep aside about £1000, usually sent prior to your solicitor before they will carry out any work for you. The searches are for your benefit and will uncover potential problems in the property or surrounding area. Some of the fees go to the solicitor for their time and some for expenses such as telegraphic transfer fees for transferring funds in and out of their client accounts. Remember the cheapest solicitor is not always the best, go with a reputed individual that works efficiently and spots errors in documentation.

Refurbishment

Typically this will vary vastly with every property but going along the lines that the property is in a livable condition, it is usual that the very least you may want to give all the walls a coat and put in the basic furniture to make it live-able to your standard or into a rent-able condition.

First time buyer CONCLUSION

There are many hidden or non obvious costs, do your research, ask the right questions to the right people, and most importantly do not over commit.

See our article on Mortgage advice for first time buyer