Overall, the site is fast to use, now that the button issue is largely fixed it's easy to navigate. Question though - why make the headings with a solid blue colour? Seems a bit jarring... wouldn't a bold heading do just as well?
Another thing: If there were more links to dive right into searches at https://www.openrent.co.uk/Tenants this would be grand. As a suggestion, a standard link to the "Browse properties by location or by commute time" page would be great, and perhaps consider making the image into a link also.
One last thing: the grey text on white background is OK - but it would be better to make it a little less light. It can make legibility a problem for some folks.
Overall though, love the site - great work!
Edit: one more idea... why not make the link to the blog more prominent? Right now it's right at the bottom alongside the legalese that almost nobody looks at. Blogging may be a pretty good way of getting repeat business. It looks like you've got some pretty decent blog posts already, why not highlight this to show that you are adding content all the time? Just a thought :-)