Menu and front page

First of all, make sure you are not making changes to the theme files. Otherwise, any updates to the theme will overwrite your changes. If you are making CSS changes, the latest version of WordPress (4.7) added a custom CSS option which you can access by going to Appearance → Customizer → Additional CSS. Copy any CSS rules that you want to override in there, and make your changes there. If you need to make changes to the .php files, then create a child theme and make your changes to a copy of the file you want to modify.

You say that the menu items used to “stretch” across the width of the menu bar. Do you mean that they were equally spaced apart? You can try adding these two rules:

#branding .only-search + #access div {
   padding-right: 0;
}
#menu-london-folk-festival {
   width: 100%;
   display: -webkit-flex;
   display: flex;
   -webkit-justify-content: space-around; /* Safari */
   justify-content:         space-around;
}

For menu bar color, add this rule:

#access {
   background: #222; /* Show a solid color for older browsers */
   background: -moz-linear-gradient(#252525, #0a0a0a);
   background: -o-linear-gradient(#252525, #0a0a0a);
   background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#252525), to(#0a0a0a)); /* older webkit syntax */
   background: -webkit-linear-gradient(#252525, #0a0a0a);
}

These are the existing values. Change them to whatever color you’d like.

For the spacing between header & content, add these two rules:

#main  {
   padding-top: 1.625em;
}
.entry-content  {
   padding-top: 1.625em;
}

Values show are what is currently in effect. Change as you desire.

Thanks up until yesterday the menu links stretched right across the menu bar but presumably because of a theme or wordpress update a searchbox appeared on the right hand side, I’ve removed this but no matter what I do I can’t display the menu correctly again, even if I try to change themes.

Did you try adding the two CSS rules that I posted above in the first box?

Thanks

The problem wasn’t the menu parsee but the search form, removing references to the search widget etc rectified the issue.