Search engine optimization required as well as new web-design

We are a software company based in the UK and have been running this business for the past 2 years. We believe now is the time to step up and aim for the top rankings on Google.
We are currently placed page 1 on Google. We have done manual SEO from our side, however this time around we are seeking help from an expert who knows their stuff.
With regards to SEO our website may also require a whole new re-design.
We are seeking someone who has knowledge in the background of software development.