Do I need a maths a level for web development if I’m not going to uni?

The answer is that it's entirely up to the individual employer who would be hiring you into the apprenticeship. There process of getting into an apprenticeship is like being accepted into any other job - it's not like applying to university; your chances of success depend heavily on how successful you are in an interview.

Generally speaking there's no need to have a mathematics background in order to become a web developer; it's not a maths-based career. Certainly there are no employers which I'm aware of who have any particular preference either way when it comes to Maths.

Different employers obviously look for different things, but here's what most interviewers hiring an apprentice into a software engineering (Incl. web developer) role will be looking out for, and the kinds of things they'll be looking at during an interview for an apprenticeship:
[ul]
[li]Enthusiasm for the career, interest in coding/technology, and positive attitude towards learning[/li]
[li]Willingness to self-teach and research new subjects, tools and technologies[/li]
[li]Logical reasoning skills / able to be methodical about problem solving[/li]
[li]Any previous background writing code and a general understanding of computers and technology[/li]
[li]Can listen, follow instructions, and ask questions about things you don't understand[/li]
[li]Good written and verbal communication skills[/li]
[li]Decent grades at whatever Level 3 subjects you've studied (generally BTEC or A-Level)[/li]
[li]Maturity [/li]
[/ul]

In terms of making sure you're in the best possible position for the interviews you'll have for the apprenticeship (and also making sure you've got some good stuff to include on your CV as well), the other 3 subjects you've chosen for your A-levels sound like they'll give you plenty of opportunity to practice some core technical skills around web development (Programming, Databases and front-end web skills should all be covered by those) - it's more important to focus on getting good grades however. It looks great if you manage to achieve As / A*s all 3 of your A-level subjects. It also looks good if you've got any kind of portfolio/project using web technologies. If you can sit in an interview and talk through any kind of web design or software development work you've done at college or in your spare time, then that'll be an excellent talking point to the people who will be making the decision to hire you.

One thing to be aware of is that the people who make that decision won't be tutors or academics, nor will they be managers or human resources people -- they'll be senior engineers and experienced web developers who are doing that type of work full-time, so those are the people who you need to impress; generally speaking, those people know exactly what it's like to be an inexperienced junior starting out from scratch because they were in the same position as you are 20 years ago.

They'll be looking for your potential to learn and grow into a web development career, and they'll want to know that you will be able to cope with the steep learning curve and plethora of new programming languages/technologies that you'll have to pick up in those first 12 months, and that you'll be able to eventually cope solving problems by yourself -- that's what really matters to them.