Cookies panel issues

## Describe the bug
Three current bugs from following the vignette (potential to split into separate issues):
- [ ] 1. Automatically redirects to the cookies page (due to the ID issue Rich mentions below, we should update the guidance to cover it to prevent others hitting it without realising)
- [ ] 2. Once accepted there is excess whitespace at the top of the screen
- [ ] 3. There is not enough padding on the left of the text and buttons inside the banner
- [ ] 4. There is spill of some kind causing a horizontal scroll bar to appear
- [ ] 5. Need to include an example of using with a hidden tab opened from the footer

## How to reproduce

Have a draft PR with a branch with the current functions in on the apps provider dashboard - https://github.com/dfe-analytical-services/apprenticeships-provider-dashboard/pull/100

## Expected behaviour
- The cookies banner to stay at the top until a user accepts.
- When a user accepts the page doesn't change.
- There is no whitespace left once cookie option set.
- The link to more cookies information works with a bslib hidden tab and we have an example for this.

## Screenshots

Excess whitespace

Lack of margin / padding for cookies banner

Spillover on right hand side causing horizontal scroll bar

## Additional context
Suspect we'll want to update the vignette and the code to fix these, some will be bugs with the package, others just a lack of detail in the guidance.