Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
I work frequently with the deaf and blind communities and am an expert in assistive technology.
Sorry to hear you’re having trouble.
Unfortunately there are very few good options for this. They are either inexpensive and low quality, require network connection, or for the ones that can work well are very costly.
The biggest limitation is that this type of process requires considerable processing power, and most handheld or portable devices just can't work quickly enough under their own power. They all require cloud computing power, hence the need for the internet connection.
You could consider an ipad that has a 4g/lte connection (built in cellular data link) or getting a cellular based wifi hotspot to run your dictation on the ipad.
One of the few internal options (for an actual computer, not a tablet) would be to use Dragon dictation software. But this software is meant for an individual user and woul dhave trouble understanding voices and syntax that it has not been previously "trained" to.
I realize that you are in the UK, but here in the use the ADA requires that most employers and organizations make reasonable accommodations for situations such as yours, at their expense.
What I would do for you if you were to attend a meeting with me would be to set you up with a CART translator (an on site typist who transcribes everything for you), with a sign language interpreter, or with a TTY relay service. I'm not sure if you sign or not, but there are online services, typically where you'd dial in via a conference call so that they can hear the audio, then they would translate/sign back to you via a video chat (internet required) on your device, or provide transcription for you that way.