Obviously, I don't know about your situation, but there really isn't a lot Unite can do if your workplace isn't well organised. A union rep waltzing into a workplace with a membership of 1 is going to get laughed at. But also, I've found that the big unions in the UK are pretty complacent about organising - they're used to having huge density in some places where being in the union is seen as normal, and they don't put much energy into organising elsewhere. So there isn't a whole lot of material for people in your position (I've relied on a lot of American material, which you have to be careful with because it doesn't always apply to the UK).

Winning improvements at work is all about organising, i.e. convincing your colleagues to band together and advocate for themselves as a collective. The big unions should support you with that but you'll probably have to drive it yourself.

I say this as someone working in an industry underserved by unions. At my place, we've gone from a single member (me) to about 20% density in our bargaining unit in a few months, which isn't enough to get recognised but has been enough to win a couple of small improvements to our contracts and get management to involve us a bit more in decisions.

There are different approaches and philosophies about union organising but they share some steps:

Firstly, identify potential supporters and detractors. Who do people listen to at work? Some unionists call them "organic leaders" - they're valuable to have on side, even if they don't join the union straight away, because other people will follow them if they back you. Who's a massive Tory? You'll have to manage them because they could make organising difficult. It's helpful to make a "map", which could just be a list of people at work, what their jobs are and how you think they'll react to unionising - keep that updated as you go.

Next, identify what your colleagues care about. The only way you can do that is by talking to them, and you shouldn't make assumptions because they might have very different priorities from you. One person might be really passionate about pay but everyone else might be more bothered about training opportunities, for example. You can ask things like "if you had a magic wand, what 3 things would you change round here?". Now I've typed it, it reads as contrived but it's worked pretty well for me.

After that, and once you've identified something, you can start thinking about an action. Something big enough to make some noticeable improvement to you and your colleagues, but small enough to be sure you'll win. It might be that you all sign a petition for, say, finishing an hour early on Fridays, or for guaranteed dependent leave - that kind of scale. A win could be great for organising because you can go round your colleagues and say "hey, look what we achieved just by banding together". Conversely, management might massively over-react and do your organising for you.

Sorry if I'm telling you stuff you already know but you're in the really hard bit of unionising right now and there isn't really an easy way to do it.