Window seals?

[illingd]

I've bought a relatively new house and it has upvc sash windows. We get the odd draught coming through the edges. We mentioned this to a friend saying we thought we might buy better quality ones in the future, but she said we just needed them sealing properly. There is currently no seal where the window meets the brickwork.

Is my friend correct and any advice on what type of person should carry out the work?

Thanks