Required notice for employer to change my starting time?

But in the recent situation I ended up going in at 11am. It actually says in my contract they need to give me four weeks notice of shift changes. This will never realistically happen, but telling me on the Wednesday that I was in 5-6 hours earlier on the Friday was no good - especially as they’d said I was on my usual route when I asked previously (without mentioning the time change).

I’d just taken my car in for service that day and had agreed to pick it up at 8am the following morning which is pretty early for me given my shift. I wasn’t best pleased to be told on that same day that I was effectively only going to be getting 5-6 hours sleep the following night as I would already knackered from getting my car. And all because the office staff wanted to get down the pub.

Most driving jobs aren’t fun when tired in my experience, but my Friday round involves lots of pedestrianised areas and tight manoeuvres down tiny Cotswold village streets with nightmare shop awnings and building edges sticking out everywhere. It’s defo not fun when shattered and the few bumps I’ve had have all been silly ones when tired where I momentarily forgot about a bollard etc below my line of sight which I knew was there and would usually have avoided.