That's difficult to answer as a total percentage, but an estate agent typically charges around 1 - 1.5%. Solicitors work on a fixed fee, which is around £1,000 - £3,000.

Buying is much more expensive as you have to pay stamp duty (a purchase tax), which go from zero on cheap properties up to 12% on properties above £1.5M

You can see this here:

https://www.gov.uk/stamp-duty-land-tax/residential-property-rates